diff --git a/core/block.js b/core/block.js
index 6524e98f9..6a20efaf9 100644
--- a/core/block.js
+++ b/core/block.js
@@ -72,25 +72,54 @@ Blockly.Block = function(workspace, prototypeName, opt_id) {
   /** @type {boolean} */
   this.contextMenu = true;
 
-  /** @type {Blockly.Block} */
+  /**
+   * @type {Blockly.Block}
+   * @private
+   */
   this.parentBlock_ = null;
-  /** @type {!Array.<!Blockly.Block>} */
+
+  /**
+   * @type {!Array.<!Blockly.Block>}
+   * @private
+   */
   this.childBlocks_ = [];
-  /** @type {boolean} */
+
+  /** @type {boolean}
+   * @private
+   */
   this.deletable_ = true;
-  /** @type {boolean} */
+
+  /**
+   * @type {boolean}
+   * @private
+   */
   this.movable_ = true;
-  /** @type {boolean} */
+
+  /**
+   * @type {boolean}
+   * @private
+   */
   this.editable_ = true;
-  /** @type {boolean} */
+
+  /**
+   * @type {boolean}
+   * @private
+   */
   this.isShadow_ = false;
-  /** @type {boolean} */
+
+  /**
+   * @type {boolean}
+   * @private
+   */
   this.collapsed_ = false;
 
   /** @type {string|Blockly.Comment} */
   this.comment = null;
 
-  /** @type {!goog.math.Coordinate} */
+  /**
+   * @type {!goog.math.Coordinate}
+   * @private
+   */
   this.xy_ = new goog.math.Coordinate(0, 0);
 
   /** @type {!Blockly.Workspace} */
@@ -193,13 +222,13 @@ 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 j = 0, input; input = this.inputList[j]; j++) {
     input.dispose();
   }
   this.inputList.length = 0;
   // Dispose of any remaining connections (next/previous/output).
   var connections = this.getConnections_(true);
-  for (var i = 0; i < connections.length; i++) {
+  for (i = 0; i < connections.length; i++) {
     var connection = connections[i];
     if (connection.isConnected()) {
       connection.disconnect();
@@ -557,7 +586,7 @@ Blockly.Block.prototype.setConnectionsHidden = function(hidden) {
     for (var i = 0, connection; connection = myConnections[i]; i++) {
       connection.setHidden(hidden);
       if (connection.isSuperior()) {
-        var child = connection.targetBlock();
+        child = connection.targetBlock();
         if (child) {
           child.setConnectionsHidden(hidden);
         }
@@ -814,7 +843,7 @@ Blockly.Block.prototype.getInputsInline = function() {
       return false;
     }
   }
-  for (var i = 1; i < this.inputList.length; i++) {
+  for (i = 1; i < this.inputList.length; i++) {
     if (this.inputList[i - 1].type == Blockly.INPUT_VALUE &&
         this.inputList[i].type == Blockly.DUMMY_INPUT) {
       // Dummy input after a value input.  Inline them.
@@ -1020,11 +1049,11 @@ Blockly.Block.prototype.interpolate_ = function(message, args, lastDummyAlign) {
   // Add last dummy input if needed.
   if (elements.length && (typeof elements[elements.length - 1] == 'string' ||
       elements[elements.length - 1]['type'].indexOf('field_') == 0)) {
-    var input = {type: 'input_dummy'};
+    var dummyInput = {type: 'input_dummy'};
     if (lastDummyAlign) {
-      input['align'] = lastDummyAlign;
+      dummyInput['align'] = lastDummyAlign;
     }
-    elements.push(input);
+    elements.push(dummyInput);
   }
   // Lookup of alignment constants.
   var alignmentLookup = {
@@ -1034,7 +1063,7 @@ Blockly.Block.prototype.interpolate_ = function(message, args, lastDummyAlign) {
   };
   // Populate block with inputs and fields.
   var fieldStack = [];
-  for (var i = 0; i < elements.length; i++) {
+  for (i = 0; i < elements.length; i++) {
     var element = elements[i];
     if (typeof element == 'string') {
       fieldStack.push([element, undefined]);
diff --git a/core/block_svg.js b/core/block_svg.js
index d67e1acc1..f0fea7f56 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -48,16 +48,31 @@ goog.require('goog.userAgent');
  */
 Blockly.BlockSvg = function(workspace, prototypeName, opt_id) {
   // Create core elements for the block.
-  /** @type {SVGElement} */
+  /**
+   * @type {SVGElement}
+   * @private
+   */
   this.svgGroup_ = Blockly.createSvgElement('g', {}, null);
-  /** @type {SVGElement} */
+
+  /**
+   * @type {SVGElement}
+   * @private
+   */
   this.svgPathDark_ = Blockly.createSvgElement('path',
       {'class': 'blocklyPathDark', 'transform': 'translate(1,1)'},
       this.svgGroup_);
-  /** @type {SVGElement} */
+
+  /**
+   * @type {SVGElement}
+   * @private
+   */
   this.svgPath_ = Blockly.createSvgElement('path', {'class': 'blocklyPath'},
       this.svgGroup_);
-  /** @type {SVGElement} */
+
+  /**
+   * @type {SVGElement}
+   * @private
+   */
   this.svgPathLight_ = Blockly.createSvgElement('path',
       {'class': 'blocklyPathLight'}, this.svgGroup_);
   this.svgPath_.tooltip = this;
@@ -104,7 +119,7 @@ Blockly.BlockSvg.prototype.initSvg = function() {
     input.init();
   }
   var icons = this.getIcons();
-  for (var i = 0; i < icons.length; i++) {
+  for (i = 0; i < icons.length; i++) {
     icons[i].createIcon();
   }
   this.updateColour();
@@ -365,7 +380,8 @@ Blockly.BlockSvg.prototype.snapToGrid = function() {
 /**
  * Returns a bounding box describing the dimensions of this block
  * and any blocks stacked below it.
- * @return {!{height: number, width: number}} Object with height and width properties.
+ * @return {!{height: number, width: number}} Object with height and width
+ *    properties.
  */
 Blockly.BlockSvg.prototype.getHeightWidth = function() {
   var height = this.height;
@@ -384,10 +400,10 @@ Blockly.BlockSvg.prototype.getHeightWidth = function() {
 };
 
 /**
- * Returns the coordinates of a bounding box describing the dimensions of this block
- * and any blocks stacked below it.
+ * Returns the coordinates of a bounding box describing the dimensions of this
+ * block and any blocks stacked below it.
  * @return {!{topLeft: goog.math.Coordinate, bottomRight: goog.math.Coordinate}}
- *         Object with top left and bottom right coordinates of the bounding box.
+ *    Object with top left and bottom right coordinates of the bounding box.
  */
 Blockly.BlockSvg.prototype.getBoundingRectangle = function() {
   var blockXY = this.getRelativeToSurfaceXY(this);
@@ -397,10 +413,12 @@ Blockly.BlockSvg.prototype.getBoundingRectangle = function() {
   var bottomRight;
   if (this.RTL) {
     // Width has the tab built into it already so subtract it here.
-    topLeft = new goog.math.Coordinate(blockXY.x - (blockBounds.width - tab), blockXY.y);
+    topLeft = new goog.math.Coordinate(blockXY.x - (blockBounds.width - tab),
+        blockXY.y);
     // Add the width of the tab/puzzle piece knob to the x coordinate
     // since X is the corner of the rectangle, not the whole puzzle piece.
-    bottomRight = new goog.math.Coordinate(blockXY.x + tab, blockXY.y + blockBounds.height);
+    bottomRight = new goog.math.Coordinate(blockXY.x + tab,
+        blockXY.y + blockBounds.height);
   } else {
     // Subtract the width of the tab/puzzle piece knob to the x coordinate
     // since X is the corner of the rectangle, not the whole puzzle piece.
@@ -429,7 +447,7 @@ Blockly.BlockSvg.prototype.setCollapsed = function(collapsed) {
   var COLLAPSED_INPUT_NAME = '_TEMP_COLLAPSED_INPUT';
   if (collapsed) {
     var icons = this.getIcons();
-    for (var i = 0; i < icons.length; i++) {
+    for (i = 0; i < icons.length; i++) {
       icons[i].setVisible(false);
     }
     var text = this.toString(Blockly.COLLAPSE_CHARS);
@@ -446,7 +464,7 @@ Blockly.BlockSvg.prototype.setCollapsed = function(collapsed) {
     renderList[0] = this;
   }
   if (this.rendered) {
-    for (var i = 0, block; block = renderList[i]; i++) {
+    for (var j = 0, block; block = renderList[j]; j++) {
       block.render();
     }
     // Don't bump neighbours.
@@ -479,7 +497,7 @@ Blockly.BlockSvg.prototype.tab = function(start, forward) {
       }
     }
   }
-  var i = list.indexOf(start);
+  i = list.indexOf(start);
   if (i == -1) {
     // No start location, start at the beginning or end.
     i = forward ? -1 : list.length;
@@ -774,12 +792,12 @@ Blockly.BlockSvg.prototype.moveConnections_ = function(dx, dy) {
     myConnections[i].moveBy(dx, dy);
   }
   var icons = this.getIcons();
-  for (var i = 0; i < icons.length; i++) {
+  for (i = 0; i < icons.length; i++) {
     icons[i].computeIconLocation();
   }
 
   // Recurse through all blocks attached under this one.
-  for (var i = 0; i < this.childBlocks_.length; i++) {
+  for (i = 0; i < this.childBlocks_.length; i++) {
     this.childBlocks_[i].moveConnections_(dx, dy);
   }
 };
@@ -844,7 +862,7 @@ Blockly.BlockSvg.prototype.onMouseMove_ = function(e) {
   if (Blockly.dragMode_ == Blockly.DRAG_FREE) {
     // Unrestricted dragging.
     var dxy = goog.math.Coordinate.difference(oldXY, this.dragStartXY_);
-    var group = this.getSvgRoot();
+    group = this.getSvgRoot();
     group.translate_ = 'translate(' + newXY.x + ',' + newXY.y + ')';
     group.setAttribute('transform', group.translate_ + group.skew_);
     // Drag all the nested bubbles.
@@ -860,7 +878,7 @@ Blockly.BlockSvg.prototype.onMouseMove_ = function(e) {
     var closestConnection = null;
     var localConnection = null;
     var radiusConnection = Blockly.SNAP_RADIUS;
-    for (var i = 0; i < myConnections.length; i++) {
+    for (i = 0; i < myConnections.length; i++) {
       var myConnection = myConnections[i];
       var neighbour = myConnection.closest(radiusConnection, dxy);
       if (neighbour.connection) {
diff --git a/core/blockly.js b/core/blockly.js
index 0536332d8..2f2d196b7 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -462,10 +462,10 @@ Blockly.getMainWorkspaceMetrics_ = function() {
     var bottomEdge = Math.max(contentY + contentHeight + viewHeight / 2,
                               contentY + viewHeight);
   } else {
-    var leftEdge = blockBox.x;
-    var rightEdge = leftEdge + blockBox.width;
-    var topEdge = blockBox.y;
-    var bottomEdge = topEdge + blockBox.height;
+    leftEdge = blockBox.x;
+    rightEdge = leftEdge + blockBox.width;
+    topEdge = blockBox.y;
+    bottomEdge = topEdge + blockBox.height;
   }
   var absoluteLeft = 0;
   if (!this.RTL && this.toolbox_) {
diff --git a/core/connection.js b/core/connection.js
index 25adcf49d..1cf066e09 100644
--- a/core/connection.js
+++ b/core/connection.js
@@ -37,7 +37,10 @@ goog.require('goog.dom');
  * @constructor
  */
 Blockly.Connection = function(source, type) {
-  /** @type {!Blockly.Block} */
+  /**
+   * @type {!Blockly.Block}
+   * @private
+   */
   this.sourceBlock_ = source;
   /** @type {number} */
   this.type = type;
@@ -425,7 +428,6 @@ Blockly.Connection.prototype.connect = function(otherConnection) {
   }
   this.checkConnection_(otherConnection);
   // Determine which block is superior (higher in the source stack).
-  var parentBlock, childBlock;
   if (this.isSuperior()) {
     // Superior block.
     Blockly.Connection.connect_(this, otherConnection);
@@ -837,8 +839,6 @@ Blockly.Connection.prototype.unhideAll = function() {
 Blockly.Connection.prototype.highlight = function() {
   var steps;
   if (this.type == Blockly.INPUT_VALUE || this.type == Blockly.OUTPUT_VALUE) {
-    var tabWidth = this.sourceBlock_.RTL ? -Blockly.BlockSvg.TAB_WIDTH :
-        Blockly.BlockSvg.TAB_WIDTH;
     steps = 'm 0,0 ' + Blockly.BlockSvg.TAB_PATH_DOWN + ' v 5';
 
   } else {
diff --git a/core/connection_db.js b/core/connection_db.js
index f0b69f7f5..9d143e367 100644
--- a/core/connection_db.js
+++ b/core/connection_db.js
@@ -173,20 +173,7 @@ Blockly.ConnectionDB.prototype.getNeighbours = function(connection, maxRadius) {
     pointerMid = Math.floor((pointerMin + pointerMax) / 2);
   }
 
-  // Walk forward and back on the y axis looking for the closest x,y point.
-  pointerMin = pointerMid;
-  pointerMax = pointerMid;
   var neighbours = [];
-  var sourceBlock = connection.getSourceBlock();
-  if (db.length) {
-    while (pointerMin >= 0 && checkConnection_(pointerMin)) {
-      pointerMin--;
-    }
-    do {
-      pointerMax++;
-    } while (pointerMax < db.length && checkConnection_(pointerMax));
-  }
-
   /**
    * Computes if the current connection is within the allowed radius of another
    * connection.
@@ -204,6 +191,19 @@ Blockly.ConnectionDB.prototype.getNeighbours = function(connection, maxRadius) {
     }
     return dy < maxRadius;
   }
+
+  // Walk forward and back on the y axis looking for the closest x,y point.
+  pointerMin = pointerMid;
+  pointerMax = pointerMid;
+  if (db.length) {
+    while (pointerMin >= 0 && checkConnection_(pointerMin)) {
+      pointerMin--;
+    }
+    do {
+      pointerMax++;
+    } while (pointerMax < db.length && checkConnection_(pointerMax));
+  }
+
   return neighbours;
 };
 
@@ -260,8 +260,8 @@ Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
   while (pointerMin >= 0 && this.isInYRange_(pointerMin, conn.y_, maxRadius)) {
     temp = this[pointerMin];
     if (conn.isConnectionAllowed(temp, bestRadius)) {
-        bestConnection = temp;
-        bestRadius = temp.distanceFrom(conn);
+      bestConnection = temp;
+      bestRadius = temp.distanceFrom(conn);
     }
     pointerMin--;
   }
@@ -271,8 +271,8 @@ Blockly.ConnectionDB.prototype.searchForClosest = function(conn, maxRadius,
       maxRadius)) {
     temp = this[pointerMax];
     if (conn.isConnectionAllowed(temp, bestRadius)) {
-        bestConnection = temp;
-        bestRadius = temp.distanceFrom(conn);
+      bestConnection = temp;
+      bestRadius = temp.distanceFrom(conn);
     }
     pointerMax++;
   }
diff --git a/core/contextmenu.js b/core/contextmenu.js
index 3a1fc6e95..ebd92df17 100644
--- a/core/contextmenu.js
+++ b/core/contextmenu.js
@@ -58,7 +58,7 @@ Blockly.ContextMenu.show = function(e, options, rtl) {
   */
   var menu = new goog.ui.Menu();
   menu.setRightToLeft(rtl);
-  for (var x = 0, option; option = options[x]; x++) {
+  for (var i = 0, option; option = options[i]; i++) {
     var menuItem = new goog.ui.MenuItem(option.text);
     menuItem.setRightToLeft(rtl);
     menu.addChild(menuItem, true);
diff --git a/core/events.js b/core/events.js
index 3de8bc5c3..cd6880dd8 100644
--- a/core/events.js
+++ b/core/events.js
@@ -161,7 +161,7 @@ Blockly.Events.filter = function(queueIn, forward) {
     }
   }
   // Remove null events.
-  for (var i = queue.length - 1; i >= 0; i--) {
+  for (i = queue.length - 1; i >= 0; i--) {
     if (queue[i].isNull()) {
       queue.splice(i, 1);
     }
@@ -172,7 +172,7 @@ 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 k = 1, event; event = queue[k]; k++) {
     if (event.type == Blockly.Events.CHANGE &&
         event.element == 'mutation') {
       queue.unshift(queue.splice(i, 1)[0]);
@@ -254,6 +254,7 @@ Blockly.Events.getDescendantIds_ = function(block) {
  * Decode the JSON into an event.
  * @param {!Object} json JSON representation.
  * @param {!Blockly.Workspace} workspace Target workspace for event.
+ * @return {!Blockly.Events.Abstract} the event represented by the json.
  */
 Blockly.Events.fromJson = function(json, workspace) {
   var event;
@@ -274,7 +275,7 @@ Blockly.Events.fromJson = function(json, workspace) {
       event = new Blockly.Events.Ui(null);
       break;
     default:
-      throw 'Unknown event type.'
+      throw 'Unknown event type.';
   }
   event.fromJson(json);
   event.workspaceId = workspace.id;
diff --git a/core/field.js b/core/field.js
index 30078e0f3..302ffb996 100644
--- a/core/field.js
+++ b/core/field.js
@@ -254,11 +254,11 @@ Blockly.Field.prototype.render_ = function() {
       var width = Blockly.Field.cacheWidths_[key];
     } else {
       try {
-        var width = this.textElement_.getComputedTextLength();
+        width = this.textElement_.getComputedTextLength();
       } catch (e) {
         // MSIE 11 is known to throw "Unexpected call to method or property
         // access." if Blockly is hidden.
-        var width = this.textElement_.textContent.length * 8;
+        width = this.textElement_.textContent.length * 8;
       }
       if (Blockly.Field.cacheWidths_) {
         Blockly.Field.cacheWidths_[key] = width;
@@ -269,7 +269,7 @@ Blockly.Field.prototype.render_ = function() {
           width + Blockly.BlockSvg.SEP_SPACE_X);
     }
   } else {
-    var width = 0;
+    width = 0;
   }
   this.size_.width = width;
 };
@@ -450,7 +450,7 @@ Blockly.Field.prototype.setTooltip = function(newTip) {
 /**
  * Return the absolute coordinates of the top-left corner of this field.
  * The origin (0,0) is the top-left corner of the page body.
- * @return {{!goog.math.Coordinate}} Object with .x and .y properties.
+ * @return {!goog.math.Coordinate} Object with .x and .y properties.
  * @private
  */
 Blockly.Field.prototype.getAbsoluteXY_ = function() {
diff --git a/core/field_angle.js b/core/field_angle.js
index 09cbf8ee1..5eb49a2dd 100644
--- a/core/field_angle.js
+++ b/core/field_angle.js
@@ -66,7 +66,7 @@ Blockly.FieldAngle.prototype.setValidator = function(handler) {
         if (v1 === undefined) {
           v1 = value;
         }
-        var v2 = Blockly.FieldAngle.angleValidator.call(this, v1);
+        v2 = Blockly.FieldAngle.angleValidator.call(this, v1);
         if (v2 === undefined) {
           v2 = v1;
         }
@@ -315,6 +315,6 @@ Blockly.FieldAngle.angleValidator = function(text) {
       n -= 360;
     }
     n = String(n);
-   }
+  }
   return n;
 };
diff --git a/core/field_variable.js b/core/field_variable.js
index 8e5bac966..421f9ea08 100644
--- a/core/field_variable.js
+++ b/core/field_variable.js
@@ -64,7 +64,7 @@ Blockly.FieldVariable.prototype.setValidator = function(handler) {
         if (v1 === undefined) {
           v1 = value;
         }
-        var v2 = Blockly.FieldVariable.dropdownChange.call(this, v1);
+        v2 = Blockly.FieldVariable.dropdownChange.call(this, v1);
         if (v2 === undefined) {
           v2 = v1;
         }
@@ -128,7 +128,7 @@ Blockly.FieldVariable.dropdownCreate = function() {
     var variableList =
         Blockly.Variables.allVariables(this.sourceBlock_.workspace);
   } else {
-    var variableList = [];
+    variableList = [];
   }
   // Ensure that the currently selected variable is an option.
   var name = this.getText();
diff --git a/core/inject.js b/core/inject.js
index 98935a5c9..fb3cd82d8 100644
--- a/core/inject.js
+++ b/core/inject.js
@@ -216,18 +216,18 @@ Blockly.createMainWorkspace_ = function(svg, options) {
               block.moveBy(0, overflow);
             }
             // Bump any block that's below the bottom back inside.
-            var overflow = edgeTop + metrics.viewHeight - MARGIN - blockXY.y;
+            overflow = edgeTop + metrics.viewHeight - MARGIN - blockXY.y;
             if (overflow < 0) {
               block.moveBy(0, overflow);
             }
             // Bump any block that's off the left back inside.
-            var overflow = MARGIN + edgeLeft -
+            overflow = MARGIN + edgeLeft -
                 blockXY.x - (options.RTL ? 0 : blockHW.width);
             if (overflow > 0) {
               block.moveBy(overflow, 0);
             }
             // Bump any block that's off the right back inside.
-            var overflow = edgeLeft + metrics.viewWidth - MARGIN -
+            overflow = edgeLeft + metrics.viewWidth - MARGIN -
                 blockXY.x + (options.RTL ? blockHW.width : 0);
             if (overflow < 0) {
               block.moveBy(overflow, 0);
diff --git a/core/input.js b/core/input.js
index 8ca265586..27733a949 100644
--- a/core/input.js
+++ b/core/input.js
@@ -47,7 +47,10 @@ Blockly.Input = function(type, name, block, connection) {
   this.type = type;
   /** @type {string} */
   this.name = name;
-  /** @type {!Blockly.Block} */
+  /**
+   * @type {!Blockly.Block}
+   * @private
+   */
   this.sourceBlock_ = block;
   /** @type {Blockly.Connection} */
   this.connection = connection;
diff --git a/core/mutator.js b/core/mutator.js
index a53babfd9..50586e082 100644
--- a/core/mutator.js
+++ b/core/mutator.js
@@ -115,7 +115,7 @@ Blockly.Mutator.prototype.createEditor_ = function() {
       quarkXml.appendChild(goog.dom.createDom('block', {'type': quarkName}));
     }
   } else {
-    var quarkXml = null;
+    quarkXml = null;
   }
   var workspaceOptions = {
     languageTree: quarkXml,
@@ -223,8 +223,8 @@ Blockly.Mutator.prototype.setVisible = function(visible) {
       var margin = this.workspace_.flyout_.CORNER_RADIUS * 2;
       var x = this.workspace_.flyout_.width_ + margin;
     } else {
-      var margin = 16;
-      var x = margin;
+      margin = 16;
+      x = margin;
     }
     if (this.block_.RTL) {
       x = -x;
@@ -283,7 +283,7 @@ Blockly.Mutator.prototype.workspaceChanged_ = function() {
   // When the mutator's workspace changes, update the source block.
   if (this.rootBlock_.workspace == this.workspace_) {
     Blockly.Events.setGroup(true);
-    var block = this.block_;
+    block = this.block_;
     var oldMutationDom = block.mutationToDom();
     var oldMutation = oldMutationDom && Blockly.Xml.domToText(oldMutationDom);
     // Switch off rendering while the source block is rebuilt.
diff --git a/core/options.js b/core/options.js
index 57ff21f0a..41e4edc3f 100644
--- a/core/options.js
+++ b/core/options.js
@@ -45,26 +45,26 @@ Blockly.Options = function(options) {
     var hasDisable = false;
     var hasSounds = false;
   } else {
-    var languageTree = Blockly.Options.parseToolboxTree(options['toolbox']);
-    var hasCategories = Boolean(languageTree &&
+    languageTree = Blockly.Options.parseToolboxTree(options['toolbox']);
+    hasCategories = Boolean(languageTree &&
         languageTree.getElementsByTagName('category').length);
-    var hasTrashcan = options['trashcan'];
+    hasTrashcan = options['trashcan'];
     if (hasTrashcan === undefined) {
       hasTrashcan = hasCategories;
     }
-    var hasCollapse = options['collapse'];
+    hasCollapse = options['collapse'];
     if (hasCollapse === undefined) {
       hasCollapse = hasCategories;
     }
-    var hasComments = options['comments'];
+    hasComments = options['comments'];
     if (hasComments === undefined) {
       hasComments = hasCategories;
     }
-    var hasDisable = options['disable'];
+    hasDisable = options['disable'];
     if (hasDisable === undefined) {
       hasDisable = hasCategories;
     }
-    var hasSounds = options['sounds'];
+    hasSounds = options['sounds'];
     if (hasSounds === undefined) {
       hasSounds = true;
     }
diff --git a/core/toolbox.js b/core/toolbox.js
index 2d765da6e..32a10f177 100644
--- a/core/toolbox.js
+++ b/core/toolbox.js
@@ -285,7 +285,7 @@ Blockly.Toolbox.prototype.addColour_ = function(opt_tree) {
       if (this.hasColours_) {
         var border = '8px solid ' + (child.hexColour || '#ddd');
       } else {
-        var border = 'none';
+        border = 'none';
       }
       if (this.workspace_.RTL) {
         element.style.borderRight = border;
@@ -321,7 +321,7 @@ Blockly.Toolbox.prototype.getClientRect = function() {
     return new goog.math.Rect(toolboxRect.left, -BIG_NUM, width, BIG_NUM * 2);
   }
   // LTR
-  var width = BIG_NUM + toolboxRect.width + toolboxRect.left;
+  width = BIG_NUM + toolboxRect.width + toolboxRect.left;
   return new goog.math.Rect(-BIG_NUM, -BIG_NUM, width, BIG_NUM * 2);
 };
 
diff --git a/core/tooltip.js b/core/tooltip.js
index 6e520e65b..86da01d65 100644
--- a/core/tooltip.js
+++ b/core/tooltip.js
@@ -317,7 +317,7 @@ Blockly.Tooltip.wrap_ = function(text, limit) {
     // Seed the list with evenly spaced linebreaks.
     var steps = words.length / lineCount;
     var insertedBreaks = 1;
-    for (var i = 0; i < words.length - 1; i++) {
+    for (i = 0; i < words.length - 1; i++) {
       if (insertedBreaks < (i + 1.5) / steps) {
         insertedBreaks++;
         wordBreaks[i] = true;
@@ -358,7 +358,7 @@ Blockly.Tooltip.wrapScore_ = function(words, wordBreaks, limit) {
   var maxLength = Math.max.apply(Math, lineLengths);
 
   var score = 0;
-  for (var i = 0; i < lineLengths.length; i++) {
+  for (i = 0; i < lineLengths.length; i++) {
     // Optimize for width.
     // -2 points per char over limit (scaled to the power of 1.5).
     score -= Math.pow(Math.abs(limit - lineLengths[i]), 1.5) * 2;
diff --git a/core/trashcan.js b/core/trashcan.js
index 429d613c6..a192deb81 100644
--- a/core/trashcan.js
+++ b/core/trashcan.js
@@ -167,7 +167,7 @@ Blockly.Trashcan.prototype.createDom = function() {
   body.setAttributeNS('http://www.w3.org/1999/xlink', 'xlink:href',
       this.workspace_.options.pathToMedia + Blockly.SPRITE.url);
 
-  var clip = Blockly.createSvgElement('clipPath',
+  clip = Blockly.createSvgElement('clipPath',
       {'id': 'blocklyTrashLidClipPath' + rnd},
       this.svgGroup_);
   Blockly.createSvgElement('rect',
diff --git a/core/utils.js b/core/utils.js
index aecc851b5..a53256867 100644
--- a/core/utils.js
+++ b/core/utils.js
@@ -104,7 +104,7 @@ Blockly.bindEvent_ = function(node, name, thisObject, func) {
       func.call(thisObject, e);
     };
   } else {
-    var wrapFunc = func;
+    wrapFunc = func;
   }
   node.addEventListener(name, wrapFunc, false);
   var bindData = [[node, name, wrapFunc]];
@@ -295,11 +295,11 @@ Blockly.createSvgElement = function(name, attrs, parent, opt_workspace) {
  * @param {boolean} selectable Whether elements on the page can be selected.
  */
 Blockly.setPageSelectable = function(selectable) {
-    if (selectable) {
-      Blockly.removeClass_(document.body, 'blocklyNonSelectable');
-    } else {
-      Blockly.addClass_(document.body, 'blocklyNonSelectable');
-    }
+  if (selectable) {
+    Blockly.removeClass_(document.body, 'blocklyNonSelectable');
+  } else {
+    Blockly.addClass_(document.body, 'blocklyNonSelectable');
+  }
 };
 
 /**
@@ -374,8 +374,8 @@ Blockly.commonWordPrefix = function(array, opt_shortest) {
       wordPrefix = len + 1;
     }
   }
-  for (var i = 1; i < array.length; i++) {
-    var letter = array[i][len];
+  for (i = 1; i < array.length; i++) {
+    letter = array[i][len];
     if (letter && letter != ' ') {
       return wordPrefix;
     }
@@ -409,8 +409,8 @@ Blockly.commonWordSuffix = function(array, opt_shortest) {
       wordPrefix = len + 1;
     }
   }
-  for (var i = 1; i < array.length; i++) {
-    var letter = array[i].charAt(array[i].length - len - 1);
+  for (i = 1; i < array.length; i++) {
+    letter = array[i].charAt(array[i].length - len - 1);
     if (letter && letter != ' ') {
       return wordPrefix;
     }
@@ -478,7 +478,7 @@ Blockly.tokenizeInterpolation = function(message) {
       }
     }
   }
-  var text = buffer.join('');
+  text = buffer.join('');
   if (text) {
     tokens.push(text);
   }
@@ -488,7 +488,7 @@ Blockly.tokenizeInterpolation = function(message) {
 /**
  * Generate a unique ID.  This should be globally unique.
  * 87 characters ^ 20 length > 128 bits (better than a UUID).
- * @return {string}
+ * @return {string} A globally unique ID string.
  */
 Blockly.genUid = function() {
   var length = 20;
diff --git a/core/variables.js b/core/variables.js
index 12b8eeb06..e4048a995 100644
--- a/core/variables.js
+++ b/core/variables.js
@@ -123,12 +123,12 @@ Blockly.Variables.flyoutCategory = function(workspace) {
       // <block type="variables_get" gap="24">
       //   <field name="VAR">item</field>
       // </block>
-      var block = goog.dom.createDom('block');
+      block = goog.dom.createDom('block');
       block.setAttribute('type', 'variables_get');
       if (Blockly.Blocks['variables_set']) {
         block.setAttribute('gap', 24);
       }
-      var field = goog.dom.createDom('field', null, variableList[i]);
+      field = goog.dom.createDom('field', null, variableList[i]);
       field.setAttribute('name', 'VAR');
       block.appendChild(field);
       xmlList.push(block);
diff --git a/core/workspace.js b/core/workspace.js
index 6f34a02e2..66a49ea99 100644
--- a/core/workspace.js
+++ b/core/workspace.js
@@ -43,15 +43,30 @@ Blockly.Workspace = function(opt_options) {
   this.options = opt_options || {};
   /** @type {boolean} */
   this.RTL = !!this.options.RTL;
-  /** @type {!Array.<!Blockly.Block>} */
+  /**
+   * @type {!Array.<!Blockly.Block>}
+   * @private
+   */
   this.topBlocks_ = [];
-  /** @type {!Array.<!Function>} */
+  /**
+   * @type {!Array.<!Function>}
+   * @private
+   */
   this.listeners_ = [];
-  /** @type {!Array.<!Blockly.Events.Abstract>} */
+  /**
+   * @type {!Array.<!Blockly.Events.Abstract>}
+   * @private
+   */
   this.undoStack_ = [];
-  /** @type {!Array.<!Blockly.Events.Abstract>} */
+  /**
+   * @type {!Array.<!Blockly.Events.Abstract>}
+   * @private
+   */
   this.redoStack_ = [];
-  /** @type {!Object} */
+  /**
+   * @type {!Object}
+   * @private
+   */
   this.blockDB_ = Object.create(null);
 };
 
@@ -204,14 +219,14 @@ Blockly.Workspace.prototype.remainingCapacity = function() {
 Blockly.Workspace.prototype.undo = function(redo) {
   var inputStack = redo ? this.redoStack_ : this.undoStack_;
   var outputStack = redo ? this.undoStack_ : this.redoStack_;
-  var event = inputStack.pop();
-  if (!event) {
+  var inputEvent = inputStack.pop();
+  if (!inputEvent) {
     return;
   }
-  var events = [event];
+  var events = [inputEvent];
   // Do another undo/redo if the next one is of the same group.
-  while (inputStack.length && event.group &&
-      event.group == inputStack[inputStack.length - 1].group) {
+  while (inputStack.length && inputEvent.group &&
+      inputEvent.group == inputStack[inputStack.length - 1].group) {
     events.push(inputStack.pop());
   }
   // Push these popped events on the opposite stack.
@@ -220,7 +235,7 @@ Blockly.Workspace.prototype.undo = function(redo) {
   }
   events = Blockly.Events.filter(events, redo);
   Blockly.Events.recordUndo = false;
-  for (var i = 0, event; event = events[i]; i++) {
+  for (i = 0; event = events[i]; i++) {
     event.run(redo);
   }
   Blockly.Events.recordUndo = true;
diff --git a/core/workspace_svg.js b/core/workspace_svg.js
index af0580b05..12e52cba3 100644
--- a/core/workspace_svg.js
+++ b/core/workspace_svg.js
@@ -413,7 +413,7 @@ Blockly.WorkspaceSvg.prototype.traceOn = function(armed) {
   }
   if (armed) {
     this.traceWrapper_ = Blockly.bindEvent_(this.svgBlockCanvas_,
-        'blocklySelectChange', this, function() {this.traceOn_ = false});
+        'blocklySelectChange', this, function() {this.traceOn_ = false;});
   }
 };
 
@@ -486,7 +486,7 @@ Blockly.WorkspaceSvg.prototype.paste = 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 j = 0, connection; connection = connections[j]; j++) {
           var neighbour = connection.closest(Blockly.SNAP_RADIUS,
               new goog.math.Coordinate(blockX, blockY));
           if (neighbour.connection) {
@@ -538,7 +538,6 @@ Blockly.WorkspaceSvg.prototype.recordDeleteAreas = function() {
  * @return {boolean} True if event is in a delete area.
  */
 Blockly.WorkspaceSvg.prototype.isDeleteArea = function(e) {
-  var isDelete = false;
   var xy = new goog.math.Coordinate(e.clientX, e.clientY);
   if (this.deleteAreaTrash_) {
     if (this.deleteAreaTrash_.contains(xy)) {
@@ -809,7 +808,7 @@ Blockly.WorkspaceSvg.prototype.showContextMenu_ = function(e) {
       }
     }
   }
-  for (var i = 0; i < topBlocks.length; i++) {
+  for (i = 0; i < topBlocks.length; i++) {
     addDeletableBlocks(topBlocks[i]);
   }
   var deleteOption = {
diff --git a/core/xml.js b/core/xml.js
index 3e9e3cdc2..5f4d9a987 100644
--- a/core/xml.js
+++ b/core/xml.js
@@ -109,7 +109,7 @@ Blockly.Xml.blockToDom = function(block) {
     element.appendChild(dataElement);
   }
 
-  for (var i = 0, input; input = block.inputList[i]; i++) {
+  for (i = 0; input = block.inputList[i]; i++) {
     var container;
     var empty = true;
     if (input.type == Blockly.DUMMY_INPUT) {
@@ -156,11 +156,11 @@ Blockly.Xml.blockToDom = function(block) {
 
   var nextBlock = block.getNextBlock();
   if (nextBlock) {
-    var container = goog.dom.createDom('next', null,
+    container = goog.dom.createDom('next', null,
         Blockly.Xml.blockToDom(nextBlock));
     element.appendChild(container);
   }
-  var shadow = block.nextConnection && block.nextConnection.getShadowDom();
+  shadow = block.nextConnection && block.nextConnection.getShadowDom();
   if (shadow && (!nextBlock || !nextBlock.isShadow())) {
     container.appendChild(Blockly.Xml.cloneShadow_(shadow));
   }
@@ -337,7 +337,7 @@ Blockly.Xml.domToBlock = function(xmlBlock, workspace) {
     for (var i = blocks.length - 1; i >= 0; i--) {
       blocks[i].initSvg();
     }
-    for (var i = blocks.length - 1; i >= 0; i--) {
+    for (i = blocks.length - 1; i >= 0; i--) {
       blocks[i].render(false);
     }
     // Populating the connection database may be defered until after the blocks
@@ -386,7 +386,6 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
     // Find any enclosed blocks or shadows in this tag.
     var childBlockNode = null;
     var childShadowNode = null;
-    var shadowActive = false;
     for (var j = 0, grandchildNode; grandchildNode = xmlChild.childNodes[j];
          j++) {
       if (grandchildNode.nodeType == 1) {
@@ -400,7 +399,6 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
     // Use the shadow block if there is no child block.
     if (!childBlockNode && childShadowNode) {
       childBlockNode = childShadowNode;
-      shadowActive = true;
     }
 
     var name = xmlChild.getAttribute('name');
diff --git a/core/zoom_controls.js b/core/zoom_controls.js
index d50110829..31f06fa9b 100644
--- a/core/zoom_controls.js
+++ b/core/zoom_controls.js
@@ -131,7 +131,7 @@ Blockly.ZoomControls.prototype.createDom = function() {
   zoomoutSvg.setAttributeNS('http://www.w3.org/1999/xlink', 'xlink:href',
       workspace.options.pathToMedia + Blockly.SPRITE.url);
 
-  var clip = Blockly.createSvgElement('clipPath',
+  clip = Blockly.createSvgElement('clipPath',
       {'id': 'blocklyZoominClipPath' + rnd},
       this.svgGroup_);
   Blockly.createSvgElement('rect',
@@ -147,7 +147,7 @@ Blockly.ZoomControls.prototype.createDom = function() {
   zoominSvg.setAttributeNS('http://www.w3.org/1999/xlink', 'xlink:href',
       workspace.options.pathToMedia + Blockly.SPRITE.url);
 
-  var clip = Blockly.createSvgElement('clipPath',
+  clip = Blockly.createSvgElement('clipPath',
       {'id': 'blocklyZoomresetClipPath' + rnd},
       this.svgGroup_);
   Blockly.createSvgElement('rect',