diff --git a/.eslintrc.json b/.eslintrc.json
index 3df051d4a..63bfb43b7 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -61,8 +61,6 @@
         "space-infix-ops": ["error"],
         "_comment": "Blockly uses 'use strict' in files",
         "strict": ["off"],
-        "_comment": "Blockly often uses cond-assignment in loops",
-        "no-cond-assign": ["off"],
         "_comment": "Closure style allows redeclarations",
         "no-redeclare": ["off"],
         "valid-jsdoc": ["error", {"requireReturn": false}],
diff --git a/blocks/procedures.js b/blocks/procedures.js
index 4b6e44975..7487a0c92 100644
--- a/blocks/procedures.js
+++ b/blocks/procedures.js
@@ -139,7 +139,7 @@ Blockly.Blocks['procedures_defnoreturn'] = {
   domToMutation: function(xmlElement) {
     this.arguments_ = [];
     this.argumentVarModels_ = [];
-    for (var i = 0, childNode; childNode = xmlElement.childNodes[i]; i++) {
+    for (var i = 0, childNode; (childNode = xmlElement.childNodes[i]); i++) {
       if (childNode.nodeName.toLowerCase() == 'arg') {
         var varName = childNode.getAttribute('name');
         var varId = childNode.getAttribute('varid') || childNode.getAttribute('varId');
@@ -354,7 +354,7 @@ Blockly.Blocks['procedures_defnoreturn'] = {
     // Update the mutator's variables if the mutator is open.
     if (this.mutator && this.mutator.isVisible()) {
       var blocks = this.mutator.workspace_.getAllBlocks(false);
-      for (var i = 0, block; block = blocks[i]; i++) {
+      for (var i = 0, block; (block = blocks[i]); i++) {
         if (block.type == 'procedures_mutatorarg' &&
             Blockly.Names.equals(oldName, block.getFieldValue('NAME'))) {
           block.setFieldValue(newName, 'NAME');
@@ -859,7 +859,7 @@ Blockly.Blocks['procedures_callnoreturn'] = {
     this.renameProcedure(this.getProcedureCall(), name);
     var args = [];
     var paramIds = [];
-    for (var i = 0, childNode; childNode = xmlElement.childNodes[i]; i++) {
+    for (var i = 0, childNode; (childNode = xmlElement.childNodes[i]); i++) {
       if (childNode.nodeName.toLowerCase() == 'arg') {
         args.push(childNode.getAttribute('name'));
         paramIds.push(childNode.getAttribute('paramId'));
diff --git a/blocks/text.js b/blocks/text.js
index 21a4e4df5..fe4b9c97f 100644
--- a/blocks/text.js
+++ b/blocks/text.js
@@ -638,8 +638,8 @@ Blockly.Constants.Text.QUOTE_IMAGE_MIXIN = {
    * @this {Blockly.Block}
    */
   quoteField_: function(fieldName) {
-    for (var i = 0, input; input = this.inputList[i]; i++) {
-      for (var j = 0, field; field = input.fieldRow[j]; j++) {
+    for (var i = 0, input; (input = this.inputList[i]); i++) {
+      for (var j = 0, field; (field = input.fieldRow[j]); j++) {
         if (fieldName == field.name) {
           input.insertFieldAt(j, this.newQuote_(true));
           input.insertFieldAt(j + 2, this.newQuote_(false));
diff --git a/core/block.js b/core/block.js
index 9c1cdb38f..46893575a 100644
--- a/core/block.js
+++ b/core/block.js
@@ -359,13 +359,13 @@ Blockly.Block.prototype.dispose = function(healStack) {
     }
     // Then dispose of myself.
     // Dispose of all inputs and their fields.
-    for (var i = 0, input; input = this.inputList[i]; i++) {
+    for (var i = 0, input; (input = this.inputList[i]); i++) {
       input.dispose();
     }
     this.inputList.length = 0;
     // Dispose of any remaining connections (next/previous/output).
     var connections = this.getConnections_(true);
-    for (var i = 0, connection; connection = connections[i]; i++) {
+    for (var i = 0, connection; (connection = connections[i]); i++) {
       connection.dispose();
     }
   } finally {
@@ -384,8 +384,8 @@ Blockly.Block.prototype.dispose = function(healStack) {
  * @public
  */
 Blockly.Block.prototype.initModel = function() {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       if (field.initModel) {
         field.initModel();
       }
@@ -516,7 +516,7 @@ Blockly.Block.prototype.getConnections_ = function(_all) {
   if (this.nextConnection) {
     myConnections.push(this.nextConnection);
   }
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.connection) {
       myConnections.push(input.connection);
     }
@@ -567,7 +567,7 @@ Blockly.Block.prototype.getParent = function() {
  * @return {Blockly.Input} The input that connects to the specified block.
  */
 Blockly.Block.prototype.getInputWithBlock = function(block) {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.connection && input.connection.targetBlock() == block) {
       return input;
     }
@@ -618,7 +618,7 @@ Blockly.Block.prototype.getPreviousBlock = function() {
  * @package
  */
 Blockly.Block.prototype.getFirstStatementConnection = function() {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.connection && input.connection.type == Blockly.NEXT_STATEMENT) {
       return input.connection;
     }
@@ -669,7 +669,7 @@ Blockly.Block.prototype.getChildren = function(ordered) {
     return this.childBlocks_;
   }
   var blocks = [];
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.connection) {
       var child = input.connection.targetBlock();
       if (child) {
@@ -732,7 +732,7 @@ Blockly.Block.prototype.setParent = function(newParent) {
 Blockly.Block.prototype.getDescendants = function(ordered) {
   var blocks = [this];
   var childBlocks = this.getChildren(ordered);
-  for (var child, i = 0; child = childBlocks[i]; i++) {
+  for (var child, i = 0; (child = childBlocks[i]); i++) {
     blocks.push.apply(blocks, child.getDescendants(ordered));
   }
   return blocks;
@@ -836,8 +836,8 @@ Blockly.Block.prototype.isEditable = function() {
  */
 Blockly.Block.prototype.setEditable = function(editable) {
   this.editable_ = editable;
-  for (var i = 0, input; input = this.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       field.updateEditable();
     }
   }
@@ -956,8 +956,8 @@ Blockly.Block.prototype.setOnChange = function(onchangeFn) {
  * @return {Blockly.Field} Named field, or null if field does not exist.
  */
 Blockly.Block.prototype.getField = function(name) {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       if (field.name == name) {
         return field;
       }
@@ -973,8 +973,8 @@ Blockly.Block.prototype.getField = function(name) {
  */
 Blockly.Block.prototype.getVars = function() {
   var vars = [];
-  for (var i = 0, input; input = this.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       if (field.referencesVariables()) {
         vars.push(field.getValue());
       }
@@ -990,8 +990,8 @@ Blockly.Block.prototype.getVars = function() {
  */
 Blockly.Block.prototype.getVarModels = function() {
   var vars = [];
-  for (var i = 0, input; input = this.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       if (field.referencesVariables()) {
         var model = this.workspace.getVariableById(
             /** @type {string} */ (field.getValue()));
@@ -1013,8 +1013,8 @@ Blockly.Block.prototype.getVarModels = function() {
  * @package
  */
 Blockly.Block.prototype.updateVarName = function(variable) {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       if (field.referencesVariables() &&
           variable.getId() == field.getValue()) {
         field.refreshVariableName();
@@ -1031,8 +1031,8 @@ Blockly.Block.prototype.updateVarName = function(variable) {
  *     an updated name.
  */
 Blockly.Block.prototype.renameVarById = function(oldId, newId) {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       if (field.referencesVariables() &&
           oldId == field.getValue()) {
         field.setValue(newId);
@@ -1277,8 +1277,8 @@ Blockly.Block.prototype.toString = function(opt_maxLength, opt_emptyToken) {
   if (this.collapsed_) {
     text.push(this.getInput('_TEMP_COLLAPSED_INPUT').fieldRow[0].getText());
   } else {
-    for (var i = 0, input; input = this.inputList[i]; i++) {
-      for (var j = 0, field; field = input.fieldRow[j]; j++) {
+    for (var i = 0, input; (input = this.inputList[i]); i++) {
+      for (var j = 0, field; (field = input.fieldRow[j]); j++) {
         text.push(field.getText());
       }
       if (input.connection) {
@@ -1573,11 +1573,9 @@ Blockly.Block.prototype.interpolate_ = function(message, args, lastDummyAlign,
               field = Blockly.fieldRegistry.fromJson(element);
 
               // Unknown field.
-              if (!field) {
-                if (element['alt']) {
-                  element = element['alt'];
-                  altRepeat = true;
-                }
+              if (!field && element['alt']) {
+                element = element['alt'];
+                altRepeat = true;
               }
           }
         }
@@ -1589,13 +1587,12 @@ Blockly.Block.prototype.interpolate_ = function(message, args, lastDummyAlign,
           input.setCheck(element['check']);
         }
         if (element['align']) {
-          var align = !!element['align'] && element['align'].toUpperCase();
-          var alignment = alignmentLookup[align];
-          if (alignment != undefined) {
-            input.setAlign(alignment);
-          } else {
+          var alignment = alignmentLookup[element['align'].toUpperCase()];
+          if (alignment === undefined) {
             console.warn(warningPrefix + 'Illegal align value: ',
                 element['align']);
+          } else {
+            input.setAlign(alignment);
           }
         }
         for (var j = 0; j < fieldStack.length; j++) {
@@ -1640,7 +1637,7 @@ Blockly.Block.prototype.moveInputBefore = function(name, refName) {
   // Find both inputs.
   var inputIndex = -1;
   var refIndex = refName ? -1 : this.inputList.length;
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.name == name) {
       inputIndex = i;
       if (refIndex != -1) {
@@ -1693,11 +1690,10 @@ Blockly.Block.prototype.moveNumberedInputBefore = function(
  * Remove an input from this block.
  * @param {string} name The name of the input.
  * @param {boolean=} opt_quiet True to prevent error if input is not present.
- * @throws {Error} if the input is not present and
- *     opt_quiet is not true.
+ * @throws {Error} if the input is not present and opt_quiet is not true.
  */
 Blockly.Block.prototype.removeInput = function(name, opt_quiet) {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.name == name) {
       input.dispose();
       this.inputList.splice(i, 1);
@@ -1715,7 +1711,7 @@ Blockly.Block.prototype.removeInput = function(name, opt_quiet) {
  * @return {Blockly.Input} The input object, or null if input does not exist.
  */
 Blockly.Block.prototype.getInput = function(name) {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (input.name == name) {
       return input;
     }
@@ -1827,7 +1823,7 @@ Blockly.Block.prototype.allInputsFilled = function(opt_shadowBlocksAreFilled) {
   }
 
   // Recursively check each input block of the current block.
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     if (!input.connection) {
       continue;
     }
diff --git a/core/block_dragger.js b/core/block_dragger.js
index 9e881c6b3..fb1a78e28 100644
--- a/core/block_dragger.js
+++ b/core/block_dragger.js
@@ -120,7 +120,7 @@ Blockly.BlockDragger.initIconData_ = function(block) {
   // Build a list of icons that need to be moved and where they started.
   var dragIconData = [];
   var descendants = block.getDescendants(false);
-  for (var i = 0, descendant; descendant = descendants[i]; i++) {
+  for (var i = 0, descendant; (descendant = descendants[i]); i++) {
     var icons = descendant.getIcons();
     for (var j = 0; j < icons.length; j++) {
       var data = {
diff --git a/core/block_events.js b/core/block_events.js
index 7c80dfca7..beff260af 100644
--- a/core/block_events.js
+++ b/core/block_events.js
@@ -273,7 +273,7 @@ Blockly.Events.Create.prototype.run = function(forward) {
     xml.appendChild(this.xml);
     Blockly.Xml.domToWorkspace(xml, workspace);
   } else {
-    for (var i = 0, id; id = this.ids[i]; i++) {
+    for (var i = 0, id; (id = this.ids[i]); i++) {
       var block = workspace.getBlockById(id);
       if (block) {
         block.dispose(false);
@@ -349,7 +349,7 @@ Blockly.Events.Delete.prototype.fromJson = function(json) {
 Blockly.Events.Delete.prototype.run = function(forward) {
   var workspace = this.getEventWorkspace_();
   if (forward) {
-    for (var i = 0, id; id = this.ids[i]; i++) {
+    for (var i = 0, id; (id = this.ids[i]); i++) {
       var block = workspace.getBlockById(id);
       if (block) {
         block.dispose(false);
diff --git a/core/block_svg.js b/core/block_svg.js
index 2a2a83c9c..d568207fd 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -258,7 +258,7 @@ Blockly.BlockSvg.prototype.initSvg = function() {
   if (!this.workspace.rendered) {
     throw TypeError('Workspace is headless.');
   }
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     input.init();
   }
   var icons = this.getIcons();
@@ -621,7 +621,7 @@ Blockly.BlockSvg.prototype.getBoundingRectangle = function() {
  * A dirty field is a field that needs to be re-rendererd.
  */
 Blockly.BlockSvg.prototype.markDirty = function() {
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     input.markDirty();
   }
 };
@@ -636,7 +636,7 @@ Blockly.BlockSvg.prototype.setCollapsed = function(collapsed) {
   }
   var renderList = [];
   // Show/hide the inputs.
-  for (var i = 0, input; input = this.inputList[i]; i++) {
+  for (var i = 0, input; (input = this.inputList[i]); i++) {
     renderList.push.apply(renderList, input.setVisible(!collapsed));
   }
 
@@ -656,7 +656,7 @@ Blockly.BlockSvg.prototype.setCollapsed = function(collapsed) {
       var index = descendants.indexOf(nextBlock);
       descendants.splice(index, descendants.length - index);
     }
-    for (var i = 1, block; block = descendants[i]; i++) {
+    for (var i = 1, block; (block = descendants[i]); i++) {
       if (block.warning) {
         this.setWarningText(Blockly.Msg['COLLAPSED_WARNINGS_WARNING'],
             Blockly.BlockSvg.COLLAPSED_WARNING_ID);
@@ -680,7 +680,7 @@ Blockly.BlockSvg.prototype.setCollapsed = function(collapsed) {
     renderList[0] = this;
   }
   if (this.rendered) {
-    for (var i = 0, block; block = renderList[i]; i++) {
+    for (var i = 0, block; (block = renderList[i]); i++) {
       block.render();
     }
     // Don't bump neighbours.
@@ -1045,8 +1045,8 @@ Blockly.BlockSvg.prototype.applyColour = function() {
     icons[i].applyColour();
   }
 
-  for (var x = 0, input; input = this.inputList[x]; x++) {
-    for (var y = 0, field; field = input.fieldRow[y]; y++) {
+  for (var x = 0, input; (input = this.inputList[x]); x++) {
+    for (var y = 0, field; (field = input.fieldRow[y]); y++) {
       field.applyColour();
     }
   }
@@ -1071,7 +1071,7 @@ Blockly.BlockSvg.prototype.updateDisabled = function() {
     }
   }
   var children = this.getChildren(false);
-  for (var i = 0, child; child = children[i]; i++) {
+  for (var i = 0, child; (child = children[i]); i++) {
     child.updateDisabled();
   }
 };
@@ -1544,7 +1544,7 @@ Blockly.BlockSvg.prototype.getConnections_ = function(all) {
       myConnections.push(this.nextConnection);
     }
     if (all || !this.collapsed_) {
-      for (var i = 0, input; input = this.inputList[i]; i++) {
+      for (var i = 0, input; (input = this.inputList[i]); i++) {
         if (input.connection) {
           myConnections.push(input.connection);
         }
@@ -1610,7 +1610,7 @@ Blockly.BlockSvg.prototype.bumpNeighbours = function() {
   }
   // Loop through every connection on this block.
   var myConnections = this.getConnections_(false);
-  for (var i = 0, connection; connection = myConnections[i]; i++) {
+  for (var i = 0, connection; (connection = myConnections[i]); i++) {
 
     // Spider down from this block bumping all sub-blocks.
     if (connection.isConnected() && connection.isSuperior()) {
@@ -1618,7 +1618,7 @@ Blockly.BlockSvg.prototype.bumpNeighbours = function() {
     }
 
     var neighbours = connection.neighbours(Blockly.SNAP_RADIUS);
-    for (var j = 0, otherConnection; otherConnection = neighbours[j]; j++) {
+    for (var j = 0, otherConnection; (otherConnection = neighbours[j]); j++) {
 
       // If both connections are connected, that's probably fine.  But if
       // either one of them is unconnected, then there could be confusion.
diff --git a/core/blockly.js b/core/blockly.js
index fd75b34a6..5f707a500 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -470,7 +470,7 @@ Blockly.bindEventWithChecks_ = function(node, name, thisObject, func,
     // Handle each touch point separately.  If the event was a mouse event, this
     // will hand back an array with one element, which we're fine handling.
     var events = Blockly.Touch.splitEventByTouches(e);
-    for (var i = 0, event; event = events[i]; i++) {
+    for (var i = 0, event; (event = events[i]); i++) {
       if (captureIdentifier && !Blockly.Touch.shouldHandleEvent(event)) {
         continue;
       }
@@ -487,7 +487,7 @@ Blockly.bindEventWithChecks_ = function(node, name, thisObject, func,
   var bindData = [];
   if (Blockly.utils.global['PointerEvent'] &&
       (name in Blockly.Touch.TOUCH_MAP)) {
-    for (var i = 0, type; type = Blockly.Touch.TOUCH_MAP[name][i]; i++) {
+    for (var i = 0, type; (type = Blockly.Touch.TOUCH_MAP[name][i]); i++) {
       node.addEventListener(type, wrapFunc, false);
       bindData.push([node, type, wrapFunc]);
     }
@@ -506,7 +506,7 @@ Blockly.bindEventWithChecks_ = function(node, name, thisObject, func,
           e.preventDefault();
         }
       };
-      for (var i = 0, type; type = Blockly.Touch.TOUCH_MAP[name][i]; i++) {
+      for (var i = 0, type; (type = Blockly.Touch.TOUCH_MAP[name][i]); i++) {
         node.addEventListener(type, touchWrapFunc, false);
         bindData.push([node, type, touchWrapFunc]);
       }
@@ -539,7 +539,7 @@ Blockly.bindEvent_ = function(node, name, thisObject, func) {
   var bindData = [];
   if (Blockly.utils.global['PointerEvent'] &&
       (name in Blockly.Touch.TOUCH_MAP)) {
-    for (var i = 0, type; type = Blockly.Touch.TOUCH_MAP[name][i]; i++) {
+    for (var i = 0, type; (type = Blockly.Touch.TOUCH_MAP[name][i]); i++) {
       node.addEventListener(type, wrapFunc, false);
       bindData.push([node, type, wrapFunc]);
     }
@@ -562,7 +562,7 @@ Blockly.bindEvent_ = function(node, name, thisObject, func) {
         // Stop the browser from scrolling/zooming the page.
         e.preventDefault();
       };
-      for (var i = 0, type; type = Blockly.Touch.TOUCH_MAP[name][i]; i++) {
+      for (var i = 0, type; (type = Blockly.Touch.TOUCH_MAP[name][i]); i++) {
         node.addEventListener(type, touchWrapFunc, false);
         bindData.push([node, type, touchWrapFunc]);
       }
diff --git a/core/connection.js b/core/connection.js
index fabc9fff6..4bc0e40b7 100644
--- a/core/connection.js
+++ b/core/connection.js
@@ -496,15 +496,14 @@ Blockly.Connection.singleConnection_ = function(block, orphanBlock) {
  * @param {!Blockly.Block} startBlock The block on which to start the search.
  * @param {!Blockly.Block} orphanBlock The block that is looking for a home.
  * @return {Blockly.Connection} The suitable connection point on the chain
- *    of blocks, or null.
+ *     of blocks, or null.
  * @package
  */
 Blockly.Connection.lastConnectionInRow = function(startBlock, orphanBlock) {
   var newBlock = startBlock;
   var connection;
-  while (connection = Blockly.Connection.singleConnection_(
-      /** @type {!Blockly.Block} */ (newBlock), orphanBlock)) {
-    // '=' is intentional in line above.
+  while ((connection = Blockly.Connection.singleConnection_(
+      /** @type {!Blockly.Block} */ (newBlock), orphanBlock))) {
     newBlock = connection.targetBlock();
     if (!newBlock || newBlock.isShadow()) {
       return connection;
@@ -749,7 +748,7 @@ Blockly.Connection.prototype.toString = function() {
     msg = 'Next Connection of ';
   } else {
     var parentInput = null;
-    for (var i = 0, input; input = block.inputList[i]; i++) {
+    for (var i = 0, input; (input = block.inputList[i]); i++) {
       if (input.connection == this) {
         parentInput = input;
         break;
diff --git a/core/contextmenu.js b/core/contextmenu.js
index efbf0c981..9feee57d8 100644
--- a/core/contextmenu.js
+++ b/core/contextmenu.js
@@ -89,7 +89,7 @@ Blockly.ContextMenu.populate_ = function(options, rtl) {
   */
   var menu = new Blockly.Menu();
   menu.setRightToLeft(rtl);
-  for (var i = 0, option; option = options[i]; i++) {
+  for (var i = 0, option; (option = options[i]); i++) {
     var menuItem = new Blockly.MenuItem(option.text);
     menuItem.setRightToLeft(rtl);
     menu.addChild(menuItem, true);
diff --git a/core/events.js b/core/events.js
index d58771afa..7ebd9caa6 100644
--- a/core/events.js
+++ b/core/events.js
@@ -194,7 +194,7 @@ Blockly.Events.fire = function(event) {
 Blockly.Events.fireNow_ = function() {
   var queue = Blockly.Events.filter(Blockly.Events.FIRE_QUEUE_, true);
   Blockly.Events.FIRE_QUEUE_.length = 0;
-  for (var i = 0, event; event = queue[i]; i++) {
+  for (var i = 0, event; (event = queue[i]); i++) {
     if (!event.workspaceId) {
       continue;
     }
@@ -220,7 +220,7 @@ Blockly.Events.filter = function(queueIn, forward) {
   var mergedQueue = [];
   var hash = Object.create(null);
   // Merge duplicates.
-  for (var i = 0, event; event = queue[i]; i++) {
+  for (var i = 0, event; (event = queue[i]); i++) {
     if (!event.isNull()) {
       var key = [event.type, event.blockId, event.workspaceId].join(' ');
 
@@ -266,7 +266,7 @@ Blockly.Events.filter = function(queueIn, forward) {
   }
   // Move mutation events to the top of the queue.
   // Intentionally skip first event.
-  for (var i = 1, event; event = queue[i]; i++) {
+  for (var i = 1, event; (event = queue[i]); i++) {
     if (event.type == Blockly.Events.CHANGE &&
         event.element == 'mutation') {
       queue.unshift(queue.splice(i, 1)[0]);
@@ -280,7 +280,7 @@ Blockly.Events.filter = function(queueIn, forward) {
  * in the undo stack.  Called by Blockly.Workspace.clearUndo.
  */
 Blockly.Events.clearPendingUndo = function() {
-  for (var i = 0, event; event = Blockly.Events.FIRE_QUEUE_[i]; i++) {
+  for (var i = 0, event; (event = Blockly.Events.FIRE_QUEUE_[i]); i++) {
     event.recordUndo = false;
   }
 };
@@ -338,7 +338,7 @@ Blockly.Events.setGroup = function(state) {
 Blockly.Events.getDescendantIds = function(block) {
   var ids = [];
   var descendants = block.getDescendants(false);
-  for (var i = 0, descendant; descendant = descendants[i]; i++) {
+  for (var i = 0, descendant; (descendant = descendants[i]); i++) {
     ids[i] = descendant.id;
   }
   return ids;
@@ -420,7 +420,7 @@ Blockly.Events.disableOrphans = function(event) {
       var parent = block.getParent();
       if (parent && parent.isEnabled()) {
         var children = block.getDescendants(false);
-        for (var i = 0, child; child = children[i]; i++) {
+        for (var i = 0, child; (child = children[i]); i++) {
           child.setEnabled(true);
         }
       } else if ((block.outputConnection || block.previousConnection) &&
diff --git a/core/field_dropdown.js b/core/field_dropdown.js
index 5693d107c..379516720 100644
--- a/core/field_dropdown.js
+++ b/core/field_dropdown.js
@@ -430,7 +430,7 @@ Blockly.FieldDropdown.prototype.getOptions = function(opt_useCache) {
 Blockly.FieldDropdown.prototype.doClassValidation_ = function(opt_newValue) {
   var isValueValid = false;
   var options = this.getOptions(true);
-  for (var i = 0, option; option = options[i]; i++) {
+  for (var i = 0, option; (option = options[i]); i++) {
     // Options are tuples of human-readable text and language-neutral values.
     if (option[1] == opt_newValue) {
       isValueValid = true;
@@ -457,7 +457,7 @@ Blockly.FieldDropdown.prototype.doClassValidation_ = function(opt_newValue) {
 Blockly.FieldDropdown.prototype.doValueUpdate_ = function(newValue) {
   Blockly.FieldDropdown.superClass_.doValueUpdate_.call(this, newValue);
   var options = this.getOptions(true);
-  for (var i = 0, option; option = options[i]; i++) {
+  for (var i = 0, option; (option = options[i]); i++) {
     if (option[1] == this.value_) {
       this.selectedIndex_ = i;
     }
diff --git a/core/field_multilineinput.js b/core/field_multilineinput.js
index 9ecf70bf5..3b07937cc 100644
--- a/core/field_multilineinput.js
+++ b/core/field_multilineinput.js
@@ -146,7 +146,7 @@ Blockly.FieldMultilineInput.prototype.getDisplayText_ = function() {
 Blockly.FieldMultilineInput.prototype.render_ = function() {
   // Remove all text group children.
   var currentChild;
-  while (currentChild = this.textGroup_.firstChild) {
+  while ((currentChild = this.textGroup_.firstChild)) {
     this.textGroup_.removeChild(currentChild);
   }
 
diff --git a/core/flyout_base.js b/core/flyout_base.js
index 90ad2357d..c5e9e7236 100644
--- a/core/flyout_base.js
+++ b/core/flyout_base.js
@@ -422,7 +422,7 @@ Blockly.Flyout.prototype.hide = function() {
   }
   this.setVisible(false);
   // Delete all the event listeners.
-  for (var i = 0, listen; listen = this.listeners_[i]; i++) {
+  for (var i = 0, listen; (listen = this.listeners_[i]); i++) {
     Blockly.unbindEvent_(listen);
   }
   this.listeners_.length = 0;
@@ -466,7 +466,7 @@ Blockly.Flyout.prototype.show = function(xmlList) {
   var gaps = [];
   this.permanentlyDisabled_.length = 0;
   var default_gap = this.horizontalLayout_ ? this.GAP_X : this.GAP_Y;
-  for (var i = 0, xml; xml = xmlList[i]; i++) {
+  for (var i = 0, xml; (xml = xmlList[i]); i++) {
     if (!xml.tagName) {
       continue;
     }
@@ -517,7 +517,7 @@ Blockly.Flyout.prototype.show = function(xmlList) {
   // When the mouse is over the background, deselect all blocks.
   var deselectAll = function() {
     var topBlocks = this.workspace_.getTopBlocks(false);
-    for (var i = 0, block; block = topBlocks[i]; i++) {
+    for (var i = 0, block; (block = topBlocks[i]); i++) {
       block.removeSelect();
     }
   };
@@ -549,7 +549,7 @@ Blockly.Flyout.prototype.show = function(xmlList) {
 Blockly.Flyout.prototype.clearOldBlocks_ = function() {
   // Delete any blocks from a previous showing.
   var oldBlocks = this.workspace_.getTopBlocks(false);
-  for (var i = 0, block; block = oldBlocks[i]; i++) {
+  for (var i = 0, block; (block = oldBlocks[i]); i++) {
     if (block.workspace == this.workspace_) {
       block.dispose(false, false);
     }
@@ -563,7 +563,7 @@ Blockly.Flyout.prototype.clearOldBlocks_ = function() {
   }
   this.mats_.length = 0;
   // Delete any buttons from a previous showing.
-  for (var i = 0, button; button = this.buttons_[i]; i++) {
+  for (var i = 0, button; (button = this.buttons_[i]); i++) {
     button.dispose();
   }
   this.buttons_.length = 0;
@@ -756,7 +756,7 @@ Blockly.Flyout.prototype.moveRectToBlock_ = function(rect, block) {
  */
 Blockly.Flyout.prototype.filterForCapacity_ = function() {
   var blocks = this.workspace_.getTopBlocks(false);
-  for (var i = 0, block; block = blocks[i]; i++) {
+  for (var i = 0, block; (block = blocks[i]); i++) {
     if (this.permanentlyDisabled_.indexOf(block) == -1) {
       var enable = this.targetWorkspace_
           .isCapacityAvailable(Blockly.utils.getBlockTypeCounts(block));
diff --git a/core/flyout_vertical.js b/core/flyout_vertical.js
index 9a6b52e38..0404ff205 100644
--- a/core/flyout_vertical.js
+++ b/core/flyout_vertical.js
@@ -259,11 +259,11 @@ Blockly.VerticalFlyout.prototype.layout_ = function(contents, gaps) {
   var cursorX = this.RTL ? margin : margin + this.tabWidth_;
   var cursorY = margin;
 
-  for (var i = 0, item; item = contents[i]; i++) {
+  for (var i = 0, item; (item = contents[i]); i++) {
     if (item.type == 'block') {
       var block = item.block;
       var allBlocks = block.getDescendants(false);
-      for (var j = 0, child; child = allBlocks[j]; j++) {
+      for (var j = 0, child; (child = allBlocks[j]); j++) {
         // Mark blocks as being inside a flyout.  This is used to detect and
         // prevent the closure of the flyout if the user right-clicks on such a
         // block.
@@ -361,7 +361,7 @@ Blockly.VerticalFlyout.prototype.reflowInternal_ = function() {
   flyoutWidth += Blockly.Scrollbar.scrollbarThickness;
 
   if (this.width_ != flyoutWidth) {
-    for (var i = 0, block; block = blocks[i]; i++) {
+    for (var i = 0, block; (block = blocks[i]); i++) {
       if (this.RTL) {
         // With the flyoutWidth known, right-align the blocks.
         var oldX = block.getRelativeToSurfaceXY().x;
diff --git a/core/generator.js b/core/generator.js
index e73adfe52..8a73d5f8c 100644
--- a/core/generator.js
+++ b/core/generator.js
@@ -101,7 +101,7 @@ Blockly.Generator.prototype.workspaceToCode = function(workspace) {
   var code = [];
   this.init(workspace);
   var blocks = workspace.getTopBlocks(true);
-  for (var i = 0, block; block = blocks[i]; i++) {
+  for (var i = 0, block; (block = blocks[i]); i++) {
     var line = this.blockToCode(block);
     if (Array.isArray(line)) {
       // Value blocks return tuples of code and operator order.
diff --git a/core/gesture.js b/core/gesture.js
index c07a19bef..758aad0e8 100644
--- a/core/gesture.js
+++ b/core/gesture.js
@@ -972,7 +972,7 @@ Blockly.Gesture.prototype.getInsertionMarkers = function() {
  */
 Blockly.Gesture.inProgress = function() {
   var workspaces = Blockly.Workspace.getAll();
-  for (var i = 0, workspace; workspace = workspaces[i]; i++) {
+  for (var i = 0, workspace; (workspace = workspaces[i]); i++) {
     if (workspace.currentGesture_) {
       return true;
     }
diff --git a/core/inject.js b/core/inject.js
index ee07595e9..805200e75 100644
--- a/core/inject.js
+++ b/core/inject.js
@@ -473,7 +473,7 @@ Blockly.inject.bindDocumentEvents_ = function() {
   if (!Blockly.documentEventsBound_) {
     Blockly.bindEventWithChecks_(document, 'scroll', null, function() {
       var workspaces = Blockly.Workspace.getAll();
-      for (var i = 0, workspace; workspace = workspaces[i]; i++) {
+      for (var i = 0, workspace; (workspace = workspaces[i]); i++) {
         if (workspace.updateInverseScreenCTM) {
           workspace.updateInverseScreenCTM();
         }
diff --git a/core/input.js b/core/input.js
index 9326d05de..b8fd2e944 100644
--- a/core/input.js
+++ b/core/input.js
@@ -144,7 +144,7 @@ Blockly.Input.prototype.insertFieldAt = function(index, field, opt_name) {
  * @throws {Error} if the field is not present.
  */
 Blockly.Input.prototype.removeField = function(name) {
-  for (var i = 0, field; field = this.fieldRow[i]; i++) {
+  for (var i = 0, field; (field = this.fieldRow[i]); i++) {
     if (field.name === name) {
       field.dispose();
       this.fieldRow.splice(i, 1);
@@ -185,7 +185,7 @@ Blockly.Input.prototype.setVisible = function(visible) {
   this.visible_ = visible;
 
   var display = visible ? 'block' : 'none';
-  for (var y = 0, field; field = this.fieldRow[y]; y++) {
+  for (var y = 0, field; (field = this.fieldRow[y]); y++) {
     field.setVisible(visible);
   }
   if (this.connection) {
@@ -211,7 +211,7 @@ Blockly.Input.prototype.setVisible = function(visible) {
  * @package
  */
 Blockly.Input.prototype.markDirty = function() {
-  for (var y = 0, field; field = this.fieldRow[y]; y++) {
+  for (var y = 0, field; (field = this.fieldRow[y]); y++) {
     field.markDirty();
   }
 };
@@ -261,7 +261,7 @@ Blockly.Input.prototype.init = function() {
  * @suppress {checkTypes}
  */
 Blockly.Input.prototype.dispose = function() {
-  for (var i = 0, field; field = this.fieldRow[i]; i++) {
+  for (var i = 0, field; (field = this.fieldRow[i]); i++) {
     field.dispose();
   }
   if (this.connection) {
diff --git a/core/keyboard_nav/ast_node.js b/core/keyboard_nav/ast_node.js
index da885b59f..133591a6b 100644
--- a/core/keyboard_nav/ast_node.js
+++ b/core/keyboard_nav/ast_node.js
@@ -269,9 +269,9 @@ Blockly.ASTNode.prototype.findNextForInput_ = function() {
   var parentInput = this.location_.getParentInput();
   var block = parentInput.getSourceBlock();
   var curIdx = block.inputList.indexOf(parentInput);
-  for (var i = curIdx + 1, input; input = block.inputList[i]; i++) {
+  for (var i = curIdx + 1, input; (input = block.inputList[i]); i++) {
     var fieldRow = input.fieldRow;
-    for (var j = 0, field; field = fieldRow[j]; j++) {
+    for (var j = 0, field; (field = fieldRow[j]); j++) {
       if (field.EDITABLE) {
         return Blockly.ASTNode.createFieldNode(field);
       }
@@ -297,7 +297,7 @@ Blockly.ASTNode.prototype.findNextForField_ = function() {
   var block = location.getSourceBlock();
   var curIdx = block.inputList.indexOf(/** @type {!Blockly.Input} */ (input));
   var fieldIdx = input.fieldRow.indexOf(location) + 1;
-  for (var i = curIdx, newInput; newInput = block.inputList[i]; i++) {
+  for (var i = curIdx, newInput; (newInput = block.inputList[i]); i++) {
     var fieldRow = newInput.fieldRow;
     while (fieldIdx < fieldRow.length) {
       if (fieldRow[fieldIdx].EDITABLE) {
@@ -325,12 +325,12 @@ Blockly.ASTNode.prototype.findPrevForInput_ = function() {
   var location = this.location_.getParentInput();
   var block = location.getSourceBlock();
   var curIdx = block.inputList.indexOf(location);
-  for (var i = curIdx, input; input = block.inputList[i]; i--) {
+  for (var i = curIdx, input; (input = block.inputList[i]); i--) {
     if (input.connection && input !== location) {
       return Blockly.ASTNode.createInputNode(input);
     }
     var fieldRow = input.fieldRow;
-    for (var j = fieldRow.length - 1, field; field = fieldRow[j]; j--) {
+    for (var j = fieldRow.length - 1, field; (field = fieldRow[j]); j--) {
       if (field.EDITABLE) {
         return Blockly.ASTNode.createFieldNode(field);
       }
@@ -352,7 +352,7 @@ Blockly.ASTNode.prototype.findPrevForField_ = function() {
   var curIdx = block.inputList.indexOf(
       /** @type {!Blockly.Input} */ (parentInput));
   var fieldIdx = parentInput.fieldRow.indexOf(location) - 1;
-  for (var i = curIdx, input; input = block.inputList[i]; i--) {
+  for (var i = curIdx, input; (input = block.inputList[i]); i--) {
     if (input.connection && input !== parentInput) {
       return Blockly.ASTNode.createInputNode(input);
     }
@@ -388,7 +388,7 @@ Blockly.ASTNode.prototype.navigateBetweenStacks_ = function(forward) {
   }
   var curRoot = curLocation.getRootBlock();
   var topBlocks = curRoot.workspace.getTopBlocks(true);
-  for (var i = 0, topBlock; topBlock = topBlocks[i]; i++) {
+  for (var i = 0, topBlock; (topBlock = topBlocks[i]); i++) {
     if (curRoot.id == topBlock.id) {
       var offset = forward ? 1 : -1;
       var resultIndex = i + offset;
@@ -459,9 +459,9 @@ Blockly.ASTNode.prototype.getOutAstNodeForBlock_ = function(block) {
  */
 Blockly.ASTNode.prototype.findFirstFieldOrInput_ = function(block) {
   var inputs = block.inputList;
-  for (var i = 0, input; input = inputs[i]; i++) {
+  for (var i = 0, input; (input = inputs[i]); i++) {
     var fieldRow = input.fieldRow;
-    for (var j = 0, field; field = fieldRow[j]; j++) {
+    for (var j = 0, field; (field = fieldRow[j]); j++) {
       if (field.EDITABLE) {
         return Blockly.ASTNode.createFieldNode(field);
       }
diff --git a/core/keyboard_nav/key_map.js b/core/keyboard_nav/key_map.js
index e8bc32c54..81f92eb59 100644
--- a/core/keyboard_nav/key_map.js
+++ b/core/keyboard_nav/key_map.js
@@ -104,7 +104,7 @@ Blockly.user.keyMap.getActionByKeyCode = function(keyCode) {
  */
 Blockly.user.keyMap.getKeyByAction = function(action) {
   var keys = Object.keys(Blockly.user.keyMap.map_);
-  for (var i = 0, key; key = keys[i]; i++) {
+  for (var i = 0, key; (key = keys[i]); i++) {
     if (Blockly.user.keyMap.map_[key].name === action.name) {
       return key;
     }
@@ -120,7 +120,7 @@ Blockly.user.keyMap.getKeyByAction = function(action) {
 Blockly.user.keyMap.serializeKeyEvent = function(e) {
   var modifiers = Blockly.utils.object.values(Blockly.user.keyMap.modifierKeys);
   var key = '';
-  for (var i = 0, keyName; keyName = modifiers[i]; i++) {
+  for (var i = 0, keyName; (keyName = modifiers[i]); i++) {
     if (e.getModifierState(keyName)) {
       key += keyName;
     }
@@ -139,7 +139,7 @@ Blockly.user.keyMap.serializeKeyEvent = function(e) {
 Blockly.user.keyMap.createSerializedKey = function(keyCode, modifiers) {
   var key = '';
   var validModifiers = Blockly.utils.object.values(Blockly.user.keyMap.modifierKeys);
-  for (var i = 0, keyName; keyName = modifiers[i]; i++) {
+  for (var i = 0, keyName; (keyName = modifiers[i]); i++) {
     if (validModifiers.indexOf(keyName) > -1) {
       key += keyName;
     } else {
diff --git a/core/keyboard_nav/tab_navigate_cursor.js b/core/keyboard_nav/tab_navigate_cursor.js
index f6cf9435e..0bf65500d 100644
--- a/core/keyboard_nav/tab_navigate_cursor.js
+++ b/core/keyboard_nav/tab_navigate_cursor.js
@@ -39,7 +39,6 @@ Blockly.TabNavigateCursor = function() {
 };
 Blockly.utils.object.inherits(Blockly.TabNavigateCursor, Blockly.Cursor);
 
-
 /**
  * Find the next node in the pre order traversal.
  * @override
@@ -67,7 +66,7 @@ Blockly.TabNavigateCursor.prototype.prev = function() {
     return null;
   }
   var newNode = this.getPreviousNode_(curNode);
-  
+
   if (newNode) {
     this.setCurNode(newNode);
   }
@@ -153,7 +152,6 @@ Blockly.TabNavigateCursor.prototype.getRightMostChild_ = function(node) {
     newNode = newNode.next();
   }
   return this.getRightMostChild_(newNode);
-
 };
 
 /**
diff --git a/core/mutator.js b/core/mutator.js
index 061420dbc..3b1a1ff4b 100644
--- a/core/mutator.js
+++ b/core/mutator.js
@@ -142,7 +142,7 @@ Blockly.Mutator.prototype.createEditor_ = function() {
   // Convert the list of names into a list of XML objects for the flyout.
   if (this.quarkNames_.length) {
     var quarkXml = Blockly.utils.xml.createElement('xml');
-    for (var i = 0, quarkName; quarkName = this.quarkNames_[i]; i++) {
+    for (var i = 0, quarkName; (quarkName = this.quarkNames_[i]); i++) {
       var element = Blockly.utils.xml.createElement('block');
       element.setAttribute('type', quarkName);
       quarkXml.appendChild(element);
@@ -290,7 +290,7 @@ Blockly.Mutator.prototype.setVisible = function(visible) {
 
     this.rootBlock_ = this.block_.decompose(this.workspace_);
     var blocks = this.rootBlock_.getDescendants(false);
-    for (var i = 0, child; child = blocks[i]; i++) {
+    for (var i = 0, child; (child = blocks[i]); i++) {
       child.render();
     }
     // The root block should not be dragable or deletable.
@@ -356,7 +356,7 @@ Blockly.Mutator.prototype.workspaceChanged_ = function(e) {
   if (!this.workspace_.isDragging()) {
     var blocks = this.workspace_.getTopBlocks(false);
     var MARGIN = 20;
-    for (var b = 0, block; block = blocks[b]; b++) {
+    for (var b = 0, block; (block = blocks[b]); b++) {
       var blockXY = block.getRelativeToSurfaceXY();
       var blockHW = block.getHeightWidth();
       if (blockXY.y + blockHW.height < MARGIN) {
diff --git a/core/procedures.js b/core/procedures.js
index 6023dbe9c..5205f09f5 100644
--- a/core/procedures.js
+++ b/core/procedures.js
@@ -307,7 +307,7 @@ Blockly.Procedures.mutateCallers = function(defBlock) {
   var name = procedureBlock.getProcedureDef()[0];
   var xmlElement = defBlock.mutationToDom(true);
   var callers = Blockly.Procedures.getCallers(name, defBlock.workspace);
-  for (var i = 0, caller; caller = callers[i]; i++) {
+  for (var i = 0, caller; (caller = callers[i]); i++) {
     var oldMutationDom = caller.mutationToDom();
     var oldMutation = oldMutationDom && Blockly.Xml.domToText(oldMutationDom);
     caller.domToMutation(xmlElement);
diff --git a/core/rendered_connection.js b/core/rendered_connection.js
index 67129772e..f5d55ab1b 100644
--- a/core/rendered_connection.js
+++ b/core/rendered_connection.js
@@ -216,8 +216,8 @@ Blockly.RenderedConnection.prototype.moveBy = function(dx, dy) {
 /**
  * Move this connection to the location given by its offset within the block and
  * the location of the block's top left corner.
- * @param {!Blockly.utils.Coordinate} blockTL The location of the top left corner
- *     of the block, in workspace coordinates.
+ * @param {!Blockly.utils.Coordinate} blockTL The location of the top left
+ *     corner of the block, in workspace coordinates.
  */
 Blockly.RenderedConnection.prototype.moveToOffset = function(blockTL) {
   this.moveTo(blockTL.x + this.offsetInBlock_.x,
@@ -344,8 +344,7 @@ Blockly.RenderedConnection.prototype.setTracking = function(doTracking) {
     this.trackedState_ = Blockly.RenderedConnection.TrackedState.TRACKED;
     return;
   }
-  if (this.trackedState_ == Blockly.RenderedConnection
-      .TrackedState.TRACKED) {
+  if (this.trackedState_ == Blockly.RenderedConnection.TrackedState.TRACKED) {
     this.db_.removeConnection(this, this.y);
   }
   this.trackedState_ = Blockly.RenderedConnection.TrackedState.UNTRACKED;
diff --git a/core/theme_manager.js b/core/theme_manager.js
index d53e9cba6..3d6e09d7e 100644
--- a/core/theme_manager.js
+++ b/core/theme_manager.js
@@ -96,7 +96,7 @@ Blockly.ThemeManager.prototype.setTheme = function(theme) {
 
   // Refresh all registered Blockly UI components.
   for (var i = 0, keys = Object.keys(this.componentDB_),
-    key; key = keys[i]; i++) {
+    key; (key = keys[i]); i++) {
     for (var j = 0, component; (component = this.componentDB_[key][j]); j++) {
       var element = component.element;
       var propertyName = component.propertyName;
diff --git a/core/toolbox.js b/core/toolbox.js
index d68bec94c..59d2c2044 100644
--- a/core/toolbox.js
+++ b/core/toolbox.js
@@ -433,7 +433,7 @@ Blockly.Toolbox.prototype.position = function() {
 Blockly.Toolbox.prototype.syncTrees_ = function(treeIn, treeOut, pathToMedia) {
   var openNode = null;
   var lastElement = null;
-  for (var i = 0, childIn; childIn = treeIn.childNodes[i]; i++) {
+  for (var i = 0, childIn; (childIn = treeIn.childNodes[i]); i++) {
     if (!childIn.tagName) {
       // Skip over text.
       continue;
@@ -574,7 +574,7 @@ Blockly.Toolbox.prototype.updateColourFromTheme_ = function(opt_tree) {
   var tree = opt_tree || this.tree_;
   if (tree) {
     var children = tree.getChildren(false);
-    for (var i = 0, child; child = children[i]; i++) {
+    for (var i = 0, child; (child = children[i]); i++) {
       if (child.styleName) {
         this.setColourFromStyle_(child.styleName, child, '');
         this.addColour_();
@@ -621,7 +621,7 @@ Blockly.Toolbox.prototype.updateSelectedItemColour_ = function(tree) {
 Blockly.Toolbox.prototype.addColour_ = function(opt_tree) {
   var tree = opt_tree || this.tree_;
   var children = tree.getChildren(false);
-  for (var i = 0, child; child = children[i]; i++) {
+  for (var i = 0, child; (child = children[i]); i++) {
     var element = child.getRowElement();
     if (element) {
       if (this.hasColours_) {
diff --git a/core/trashcan.js b/core/trashcan.js
index e6e577a3a..b676626a2 100644
--- a/core/trashcan.js
+++ b/core/trashcan.js
@@ -430,7 +430,7 @@ Blockly.Trashcan.prototype.click = function() {
   }
 
   var xml = [];
-  for (var i = 0, text; text = this.contents_[i]; i++) {
+  for (var i = 0, text; (text = this.contents_[i]); i++) {
     xml[i] = Blockly.Xml.textToDom(text);
   }
   this.flyout.show(xml);
diff --git a/core/utils.js b/core/utils.js
index f633f6c35..371568b80 100644
--- a/core/utils.js
+++ b/core/utils.js
@@ -574,7 +574,7 @@ Blockly.utils.getBlockTypeCounts = function(block, opt_stripFollowing) {
       descendants.splice(index, descendants.length - index);
     }
   }
-  for (var i = 0, checkBlock; checkBlock = descendants[i]; i++) {
+  for (var i = 0, checkBlock; (checkBlock = descendants[i]); i++) {
     if (typeCountsMap[checkBlock.type]) {
       typeCountsMap[checkBlock.type]++;
     } else {
diff --git a/core/variable_map.js b/core/variable_map.js
index f52aba2e2..cb2d8d7d9 100644
--- a/core/variable_map.js
+++ b/core/variable_map.js
@@ -208,7 +208,7 @@ Blockly.VariableMap.prototype.createVariable = function(name,
  */
 Blockly.VariableMap.prototype.deleteVariable = function(variable) {
   var variableList = this.variableMap_[variable.type];
-  for (var i = 0, tempVar; tempVar = variableList[i]; i++) {
+  for (var i = 0, tempVar; (tempVar = variableList[i]); i++) {
     if (tempVar.getId() == variable.getId()) {
       variableList.splice(i, 1);
       Blockly.Events.fire(new Blockly.Events.VarDelete(variable));
@@ -228,7 +228,7 @@ Blockly.VariableMap.prototype.deleteVariableById = function(id) {
     // Check whether this variable is a function parameter before deleting.
     var variableName = variable.name;
     var uses = this.getVariableUsesById(id);
-    for (var i = 0, block; block = uses[i]; i++) {
+    for (var i = 0, block; (block = uses[i]); i++) {
       if (block.type == 'procedures_defnoreturn' ||
         block.type == 'procedures_defreturn') {
         var procedureName = block.getFieldValue('NAME');
@@ -301,7 +301,7 @@ Blockly.VariableMap.prototype.getVariable = function(name, opt_type) {
   var type = opt_type || '';
   var list = this.variableMap_[type];
   if (list) {
-    for (var j = 0, variable; variable = list[j]; j++) {
+    for (var j = 0, variable; (variable = list[j]); j++) {
       if (Blockly.Names.equals(variable.name, name)) {
         return variable;
       }
@@ -320,7 +320,7 @@ Blockly.VariableMap.prototype.getVariableById = function(id) {
   var keys = Object.keys(this.variableMap_);
   for (var i = 0; i < keys.length; i++ ) {
     var key = keys[i];
-    for (var j = 0, variable; variable = this.variableMap_[key][j]; j++) {
+    for (var j = 0, variable; (variable = this.variableMap_[key][j]); j++) {
       if (variable.getId() == id) {
         return variable;
       }
diff --git a/core/variables.js b/core/variables.js
index f15d92aff..d6ec0c8af 100644
--- a/core/variables.js
+++ b/core/variables.js
@@ -107,7 +107,7 @@ Blockly.Variables.ALL_DEVELOPER_VARS_WARNINGS_BY_BLOCK_TYPE_ = {};
 Blockly.Variables.allDeveloperVariables = function(workspace) {
   var blocks = workspace.getAllBlocks(false);
   var variableHash = Object.create(null);
-  for (var i = 0, block; block = blocks[i]; i++) {
+  for (var i = 0, block; (block = blocks[i]); i++) {
     var getDeveloperVariables = block.getDeveloperVariables;
     if (!getDeveloperVariables && block.getDeveloperVars) {
       // August 2018: getDeveloperVars() was deprecated and renamed
@@ -194,7 +194,7 @@ Blockly.Variables.flyoutCategoryBlocks = function(workspace) {
 
     if (Blockly.Blocks['variables_get']) {
       variableModelList.sort(Blockly.VariableModel.compareByName);
-      for (var i = 0, variable; variable = variableModelList[i]; i++) {
+      for (var i = 0, variable; (variable = variableModelList[i]); i++) {
         var block = Blockly.utils.xml.createElement('block');
         block.setAttribute('type', 'variables_get');
         block.setAttribute('gap', 8);
@@ -411,7 +411,7 @@ Blockly.Variables.nameUsedWithOtherType_ = function(name, type, workspace) {
   var allVariables = workspace.getVariableMap().getAllVariables();
 
   name = name.toLowerCase();
-  for (var i = 0, variable; variable = allVariables[i]; i++) {
+  for (var i = 0, variable; (variable = allVariables[i]); i++) {
     if (variable.name.toLowerCase() == name && variable.type != type) {
       return variable;
     }
@@ -432,7 +432,7 @@ Blockly.Variables.nameUsedWithAnyType_ = function(name, workspace) {
   var allVariables = workspace.getVariableMap().getAllVariables();
 
   name = name.toLowerCase();
-  for (var i = 0, variable; variable = allVariables[i]; i++) {
+  for (var i = 0, variable; (variable = allVariables[i]); i++) {
     if (variable.name.toLowerCase() == name) {
       return variable;
     }
diff --git a/core/variables_dynamic.js b/core/variables_dynamic.js
index 0d8d1548a..e7490dd19 100644
--- a/core/variables_dynamic.js
+++ b/core/variables_dynamic.js
@@ -98,7 +98,7 @@ Blockly.VariablesDynamic.flyoutCategoryBlocks = function(workspace) {
     }
     if (Blockly.Blocks['variables_get_dynamic']) {
       variableModelList.sort(Blockly.VariableModel.compareByName);
-      for (var i = 0, variable; variable = variableModelList[i]; i++) {
+      for (var i = 0, variable; (variable = variableModelList[i]); i++) {
         var block = Blockly.utils.xml.createElement('block');
         block.setAttribute('type', 'variables_get_dynamic');
         block.setAttribute('gap', 8);
diff --git a/core/warning.js b/core/warning.js
index fde0bd50c..ba3cf3ced 100644
--- a/core/warning.js
+++ b/core/warning.js
@@ -143,7 +143,7 @@ Blockly.Warning.prototype.createBubble = function() {
     // This cannot be done until the bubble is rendered on screen.
     var maxWidth = this.paragraphElement_.getBBox().width;
     for (var i = 0, textElement;
-      textElement = this.paragraphElement_.childNodes[i]; i++) {
+      (textElement = this.paragraphElement_.childNodes[i]); i++) {
 
       textElement.setAttribute('text-anchor', 'end');
       textElement.setAttribute('x', maxWidth + Blockly.Bubble.BORDER_WIDTH);
diff --git a/core/workspace.js b/core/workspace.js
index 0f7b74c9b..350229224 100644
--- a/core/workspace.js
+++ b/core/workspace.js
@@ -136,7 +136,7 @@ Blockly.Workspace = function(opt_options) {
   this.themeManager_ = this.options.parentWorkspace ?
       this.options.parentWorkspace.getThemeManager() :
       new Blockly.ThemeManager(this.options.theme || Blockly.Themes.Classic);
-  
+
   this.themeManager_.subscribeWorkspace(this);
 
   /**
@@ -251,7 +251,7 @@ Blockly.Workspace.prototype.refreshTheme = function() {
  * @private
  */
 Blockly.Workspace.prototype.updateBlockStyles_ = function(blocks) {
-  for (var i = 0, block; block = blocks[i]; i++) {
+  for (var i = 0, block; (block = blocks[i]); i++) {
     var blockStyleName = block.getStyleName();
     if (blockStyleName) {
       block.setStyle(blockStyleName);
@@ -731,13 +731,13 @@ Blockly.Workspace.prototype.undo = function(redo) {
     events.push(inputStack.pop());
   }
   // Push these popped events on the opposite stack.
-  for (var i = 0, event; event = events[i]; i++) {
+  for (var i = 0, event; (event = events[i]); i++) {
     outputStack.push(event);
   }
   events = Blockly.Events.filter(events, redo);
   Blockly.Events.recordUndo = false;
   try {
-    for (var i = 0, event; event = events[i]; i++) {
+    for (var i = 0, event; (event = events[i]); i++) {
       event.run(redo);
     }
   } finally {
@@ -788,7 +788,7 @@ Blockly.Workspace.prototype.fireChangeListener = function(event) {
       this.undoStack_.shift();
     }
   }
-  for (var i = 0, func; func = this.listeners_[i]; i++) {
+  for (var i = 0, func; (func = this.listeners_[i]); i++) {
     func(event);
   }
 };
@@ -842,7 +842,7 @@ Blockly.Workspace.prototype.getCommentById = function(id) {
 Blockly.Workspace.prototype.allInputsFilled = function(
     opt_shadowBlocksAreFilled) {
   var blocks = this.getTopBlocks(false);
-  for (var i = 0, block; block = blocks[i]; i++) {
+  for (var i = 0, block; (block = blocks[i]); i++) {
     if (!block.allInputsFilled(opt_shadowBlocksAreFilled)) {
       return false;
     }
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index 9efe86b06..4876dd0e0 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -1150,7 +1150,7 @@ Blockly.WorkspaceSvg.prototype.traceOn = function() {
 Blockly.WorkspaceSvg.prototype.highlightBlock = function(id, opt_state) {
   if (opt_state === undefined) {
     // Unhighlight all blocks.
-    for (var i = 0, block; block = this.highlightedBlocks_[i]; i++) {
+    for (var i = 0, block; (block = this.highlightedBlocks_[i]); i++) {
       block.setHighlighted(false);
     }
     this.highlightedBlocks_.length = 0;
@@ -1220,7 +1220,7 @@ Blockly.WorkspaceSvg.prototype.pasteBlock_ = function(xmlBlock) {
       do {
         var collide = false;
         var allBlocks = this.getAllBlocks(false);
-        for (var i = 0, otherBlock; otherBlock = allBlocks[i]; i++) {
+        for (var i = 0, otherBlock; (otherBlock = allBlocks[i]); i++) {
           var otherXY = otherBlock.getRelativeToSurfaceXY();
           if (Math.abs(blockX - otherXY.x) <= 1 &&
               Math.abs(blockY - otherXY.y) <= 1) {
@@ -1231,7 +1231,7 @@ Blockly.WorkspaceSvg.prototype.pasteBlock_ = function(xmlBlock) {
         if (!collide) {
           // Check for blocks in snap range to any of its connections.
           var connections = block.getConnections_(false);
-          for (var i = 0, connection; connection = connections[i]; i++) {
+          for (var i = 0, connection; (connection = connections[i]); i++) {
             var neighbour = connection.closest(Blockly.SNAP_RADIUS,
                 new Blockly.utils.Coordinate(blockX, blockY));
             if (neighbour.connection) {
@@ -1564,7 +1564,7 @@ Blockly.WorkspaceSvg.prototype.cleanUp = function() {
   Blockly.Events.setGroup(true);
   var topBlocks = this.getTopBlocks(true);
   var cursorY = 0;
-  for (var i = 0, block; block = topBlocks[i]; i++) {
+  for (var i = 0, block; (block = topBlocks[i]); i++) {
     if (!block.isMovable()) {
       continue;
     }
diff --git a/core/xml.js b/core/xml.js
index f146b7761..9d0092c10 100644
--- a/core/xml.js
+++ b/core/xml.js
@@ -51,11 +51,11 @@ Blockly.Xml.workspaceToDom = function(workspace, opt_noId) {
     xml.appendChild(variablesElement);
   }
   var comments = workspace.getTopComments(true);
-  for (var i = 0, comment; comment = comments[i]; i++) {
+  for (var i = 0, comment; (comment = comments[i]); i++) {
     xml.appendChild(comment.toXmlWithXY(opt_noId));
   }
   var blocks = workspace.getTopBlocks(true);
-  for (var i = 0, block; block = blocks[i]; i++) {
+  for (var i = 0, block; (block = blocks[i]); i++) {
     xml.appendChild(Blockly.Xml.blockToDomWithXY(block, opt_noId));
   }
   return xml;
@@ -69,7 +69,7 @@ Blockly.Xml.workspaceToDom = function(workspace, opt_noId) {
  */
 Blockly.Xml.variablesToDom = function(variableList) {
   var variables = Blockly.utils.xml.createElement('variables');
-  for (var i = 0, variable; variable = variableList[i]; i++) {
+  for (var i = 0, variable; (variable = variableList[i]); i++) {
     var element = Blockly.utils.xml.createElement('variable');
     element.appendChild(Blockly.utils.xml.createTextNode(variable.name));
     if (variable.type) {
@@ -125,8 +125,8 @@ Blockly.Xml.fieldToDom_ = function(field) {
  * @private
  */
 Blockly.Xml.allFieldsToDom_ = function(block, element) {
-  for (var i = 0, input; input = block.inputList[i]; i++) {
-    for (var j = 0, field; field = input.fieldRow[j]; j++) {
+  for (var i = 0, input; (input = block.inputList[i]); i++) {
+    for (var j = 0, field; (field = input.fieldRow[j]); j++) {
       var fieldDom = Blockly.Xml.fieldToDom_(field);
       if (fieldDom) {
         element.appendChild(fieldDom);
@@ -178,7 +178,7 @@ Blockly.Xml.blockToDom = function(block, opt_noId) {
     element.appendChild(dataElement);
   }
 
-  for (var i = 0, input; input = block.inputList[i]; i++) {
+  for (var i = 0, input; (input = block.inputList[i]); i++) {
     var container;
     var empty = true;
     if (input.type == Blockly.DUMMY_INPUT) {
@@ -402,7 +402,7 @@ Blockly.Xml.domToWorkspace = function(xml, workspace) {
   }
   var variablesFirst = true;
   try {
-    for (var i = 0, xmlChild; xmlChild = xml.childNodes[i]; i++) {
+    for (var i = 0, xmlChild; (xmlChild = xml.childNodes[i]); i++) {
       var name = xmlChild.nodeName.toLowerCase();
       var xmlChildElement = /** @type {!Element} */ (xmlChild);
       if (name == 'block' ||
@@ -595,7 +595,7 @@ Blockly.Xml.domToBlock = function(xmlBlock, workspace) {
  *     should be added.
  */
 Blockly.Xml.domToVariables = function(xmlVariables, workspace) {
-  for (var i = 0, xmlChild; xmlChild = xmlVariables.childNodes[i]; i++) {
+  for (var i = 0, xmlChild; (xmlChild = xmlVariables.childNodes[i]); i++) {
     if (xmlChild.nodeType != Blockly.utils.dom.Node.ELEMENT_NODE) {
       continue;  // Skip text nodes.
     }
@@ -625,7 +625,7 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
   block = workspace.newBlock(prototypeName, id);
 
   var blockChild = null;
-  for (var i = 0, xmlChild; xmlChild = xmlBlock.childNodes[i]; i++) {
+  for (var i = 0, xmlChild; (xmlChild = xmlBlock.childNodes[i]); i++) {
     if (xmlChild.nodeType == Blockly.utils.dom.Node.TEXT_NODE) {
       // Ignore any text at the <block> level.  It's all whitespace anyway.
       continue;
@@ -635,7 +635,7 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
     // Find any enclosed blocks or shadows in this tag.
     var childBlockElement = null;
     var childShadowElement = null;
-    for (var j = 0, grandchild; grandchild = xmlChild.childNodes[j]; j++) {
+    for (var j = 0, grandchild; (grandchild = xmlChild.childNodes[j]); j++) {
       if (grandchild.nodeType == Blockly.utils.dom.Node.ELEMENT_NODE) {
         if (grandchild.nodeName.toLowerCase() == 'block') {
           childBlockElement = /** @type {!Element} */ (grandchild);
@@ -771,7 +771,7 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
   if (xmlBlock.nodeName.toLowerCase() == 'shadow') {
     // Ensure all children are also shadows.
     var children = block.getChildren(false);
-    for (var i = 0, child; child = children[i]; i++) {
+    for (var i = 0, child; (child = children[i]); i++) {
       if (!child.isShadow()) {
         throw TypeError('Shadow block not allowed non-shadow child.');
       }
@@ -807,7 +807,7 @@ Blockly.Xml.domToField_ = function(block, fieldName, xml) {
  * @param {!Element} xmlBlock XML block element.
  */
 Blockly.Xml.deleteNext = function(xmlBlock) {
-  for (var i = 0, child; child = xmlBlock.childNodes[i]; i++) {
+  for (var i = 0, child; (child = xmlBlock.childNodes[i]); i++) {
     if (child.nodeName.toLowerCase() == 'next') {
       xmlBlock.removeChild(child);
       break;
diff --git a/tests/mocha/procedures_test.js b/tests/mocha/procedures_test.js
index 85adf8c8d..c973600b2 100644
--- a/tests/mocha/procedures_test.js
+++ b/tests/mocha/procedures_test.js
@@ -33,7 +33,7 @@ suite('Procedures', function() {
         ['procedures_defreturn', 'procedures_callreturn']
       ];
 
-      for (var i = 0, types; types = typesArray[i]; i++) {
+      for (var i = 0, types; (types = typesArray[i]); i++) {
         var context = Object.create(null);
         context.workspace = this.workspace;
         context.defType = types[0];
@@ -392,7 +392,7 @@ suite('Procedures', function() {
           // TODO: Update this for typed vars.
           var variables = this.workspace.getVariablesOfType('');
           var variableMap = this.workspace.getVariableMap();
-          for (var i = 0, variable; variable = variables[i]; i++) {
+          for (var i = 0, variable; (variable = variables[i]); i++) {
             variableMap.deleteVariable(variable);
           }
         }
diff --git a/tests/mocha/xml_procedures_test.js b/tests/mocha/xml_procedures_test.js
index 5af798c9e..b8d871c80 100644
--- a/tests/mocha/xml_procedures_test.js
+++ b/tests/mocha/xml_procedures_test.js
@@ -34,7 +34,7 @@ suite('Procedures XML', function() {
           ['procedures_defreturn', 'procedures_callreturn']
         ];
 
-        for (var i = 0, types; types = typesArray[i]; i++) {
+        for (var i = 0, types; (types = typesArray[i]); i++) {
           var context = Object.create(null);
           context.workspace = this.workspace;
           context.defType = types[0];
diff --git a/tests/mocha/xml_test.js b/tests/mocha/xml_test.js
index 84f767c31..200ba304f 100644
--- a/tests/mocha/xml_test.js
+++ b/tests/mocha/xml_test.js
@@ -442,7 +442,7 @@ suite('XML', function() {
         this.workspace.createVariable('name1', '', 'id1');
         var blocksArray = Blockly.Variables.flyoutCategoryBlocks(this.workspace);
         try {
-          for (var i = 0, xml; xml = blocksArray[i]; i++) {
+          for (var i = 0, xml; (xml = blocksArray[i]); i++) {
             Blockly.Xml.domToBlock(xml, this.workspace);
           }
         } finally {
@@ -509,7 +509,7 @@ suite('XML', function() {
         var blocksArray = Blockly.VariablesDynamic
             .flyoutCategoryBlocks(this.workspace);
         try {
-          for (var i = 0, xml; xml = blocksArray[i]; i++) {
+          for (var i = 0, xml; (xml = blocksArray[i]); i++) {
             Blockly.Xml.domToBlock(xml, this.workspace);
           }
         } finally {