diff --git a/core/block.js b/core/block.js
index 644755019..d081bc889 100644
--- a/core/block.js
+++ b/core/block.js
@@ -1551,16 +1551,15 @@ Blockly.Block.prototype.jsonInit = function(json) {
     json['extensions'] = [json['extensions']];  // Correct and continue.
   }
 
-  // Add the mutator to the block
+  // Add the mutator to the block.
   if (json['mutator'] !== undefined) {
     Blockly.Extensions.apply(json['mutator'], this, true);
   }
 
-  if (Array.isArray(json['extensions'])) {
-    var extensionNames = json['extensions'];
+  var extensionNames = json['extensions'];
+  if (Array.isArray(extensionNames)) {
     for (var j = 0; j < extensionNames.length; ++j) {
-      var extensionName = extensionNames[j];
-      Blockly.Extensions.apply(extensionName, this, false);
+      Blockly.Extensions.apply(extensionNames[j], this, false);
     }
   }
 };
diff --git a/core/block_svg.js b/core/block_svg.js
index e70ec69fe..fc4611a67 100644
--- a/core/block_svg.js
+++ b/core/block_svg.js
@@ -340,33 +340,33 @@ Blockly.BlockSvg.prototype.unselect = function() {
 
 /**
  * Block's mutator icon (if any).
- * @type {Blockly.Mutator}
+ * @type {?Blockly.Mutator}
  */
 Blockly.BlockSvg.prototype.mutator = null;
 
 /**
  * Block's comment icon (if any).
- * @type {Blockly.Comment}
+ * @type {?Blockly.Comment}
  * @deprecated August 2019. Use getCommentIcon instead.
  */
 Blockly.BlockSvg.prototype.comment = null;
 
 /**
  * Block's comment icon (if any).
- * @type {Blockly.Comment}
+ * @type {?Blockly.Comment}
  * @private
  */
 Blockly.BlockSvg.prototype.commentIcon_ = null;
 
 /**
  * Block's warning icon (if any).
- * @type {Blockly.Warning}
+ * @type {?Blockly.Warning}
  */
 Blockly.BlockSvg.prototype.warning = null;
 
 /**
  * Returns a list of mutator, comment, and warning icons.
- * @return {!Array} List of icons.
+ * @return {!Array<!Blockly.Icon>} List of icons.
  */
 Blockly.BlockSvg.prototype.getIcons = function() {
   var icons = [];
@@ -384,7 +384,7 @@ Blockly.BlockSvg.prototype.getIcons = function() {
 
 /**
  * Set parent of this block to be a new block or null.
- * @param {Blockly.Block} newParent New parent block.
+ * @param {?Blockly.Block} newParent New parent block.
  * @override
  */
 Blockly.BlockSvg.prototype.setParent = function(newParent) {
diff --git a/core/connection_db.js b/core/connection_db.js
index 4fc832bf9..4b2615725 100644
--- a/core/connection_db.js
+++ b/core/connection_db.js
@@ -84,21 +84,21 @@ Blockly.ConnectionDB.prototype.findIndexOfConnection_ = function(conn, yPos) {
 
   yPos = conn.y;
   // Walk forward and back on the y axis looking for the connection.
-  var pointerMin = bestGuess;
-  var pointerMax = bestGuess;
-  while (pointerMin >= 0 && this.connections_[pointerMin].y == yPos) {
-    if (this.connections_[pointerMin] == conn) {
-      return pointerMin;
+  var pointer = bestGuess;
+  while (pointer >= 0 && this.connections_[pointer].y == yPos) {
+    if (this.connections_[pointer] == conn) {
+      return pointer;
     }
-    pointerMin--;
+    pointer--;
   }
 
-  while (pointerMax < this.connections_.length &&
-         this.connections_[pointerMax].y == yPos) {
-    if (this.connections_[pointerMax] == conn) {
-      return pointerMax;
+  pointer = bestGuess;
+  while (pointer < this.connections_.length &&
+         this.connections_[pointer].y == yPos) {
+    if (this.connections_[pointer] == conn) {
+      return pointer;
     }
-    pointerMax++;
+    pointer++;
   }
   return -1;
 };
diff --git a/core/field_number.js b/core/field_number.js
index c5c3287a0..3ea3ef22a 100644
--- a/core/field_number.js
+++ b/core/field_number.js
@@ -222,17 +222,8 @@ Blockly.FieldNumber.prototype.setPrecision = function(precision) {
  * @private
  */
 Blockly.FieldNumber.prototype.setPrecisionInternal_ = function(precision) {
-  if (precision == null) {
-    // Number(precision) would also be 0, but set explicitly to be clear.
-    this.precision_ = 0;
-  } else {
-    precision = Number(precision);
-    if (!isNaN(precision)) {
-      this.precision_ = precision;
-    }
-  }
-
-  var precisionString = this.precision_.toLocaleString("en-US", {maximumFractionDigits: 20});
+  this.precision_ = Number(precision) || 0;
+  var precisionString = this.precision_.toLocaleString('en-US', {maximumFractionDigits: 20});
   var decimalIndex = precisionString.indexOf('.');
   if (decimalIndex == -1) {
     // If the precision is 0 (float) allow any number of decimals,
diff --git a/core/inject.js b/core/inject.js
index f11fe3075..e4acc072a 100644
--- a/core/inject.js
+++ b/core/inject.js
@@ -234,8 +234,7 @@ Blockly.bumpTopObjectsIntoBounds_ = function(workspace) {
   var scrollMetricsInWsCoords = metricsManager.getScrollMetrics(true);
   var topBlocks = workspace.getTopBoundedElements();
   for (var i = 0, block; (block = topBlocks[i]); i++) {
-    Blockly.bumpObjectIntoBounds_(
-        workspace, scrollMetricsInWsCoords, block);
+    Blockly.bumpObjectIntoBounds_(workspace, scrollMetricsInWsCoords, block);
   }
 };
 
diff --git a/core/renderers/common/info.js b/core/renderers/common/info.js
index 8600b588c..f3eac053a 100644
--- a/core/renderers/common/info.js
+++ b/core/renderers/common/info.js
@@ -210,14 +210,12 @@ Blockly.blockRendering.RenderInfo.prototype.createRows_ = function() {
 
   // Icons always go on the first row, before anything else.
   var icons = this.block_.getIcons();
-  if (icons.length) {
-    for (var i = 0, icon; (icon = icons[i]); i++) {
-      var iconInfo = new Blockly.blockRendering.Icon(this.constants_, icon);
-      if (this.isCollapsed && icon.collapseHidden) {
-        this.hiddenIcons.push(iconInfo);
-      } else {
-        activeRow.elements.push(iconInfo);
-      }
+  for (var i = 0, icon; (icon = icons[i]); i++) {
+    var iconInfo = new Blockly.blockRendering.Icon(this.constants_, icon);
+    if (this.isCollapsed && icon.collapseHidden) {
+      this.hiddenIcons.push(iconInfo);
+    } else {
+      activeRow.elements.push(iconInfo);
     }
   }
 
@@ -264,17 +262,12 @@ Blockly.blockRendering.RenderInfo.prototype.createRows_ = function() {
 Blockly.blockRendering.RenderInfo.prototype.populateTopRow_ = function() {
   var hasPrevious = !!this.block_.previousConnection;
   var hasHat = (this.block_.hat ?
-    this.block_.hat === 'cap' : this.constants_.ADD_START_HATS) &&
-    !this.outputConnection && !hasPrevious;
-  var leftSquareCorner = this.topRow.hasLeftSquareCorner(this.block_);
+      this.block_.hat === 'cap' : this.constants_.ADD_START_HATS) &&
+      !this.outputConnection && !hasPrevious;
 
-  if (leftSquareCorner) {
-    this.topRow.elements.push(
-        new Blockly.blockRendering.SquareCorner(this.constants_));
-  } else {
-    this.topRow.elements.push(
-        new Blockly.blockRendering.RoundCorner(this.constants_));
-  }
+  var cornerClass = this.topRow.hasLeftSquareCorner(this.block_) ?
+      Blockly.blockRendering.SquareCorner : Blockly.blockRendering.RoundCorner;
+  this.topRow.elements.push(new cornerClass(this.constants_));
 
   if (hasHat) {
     var hat = new Blockly.blockRendering.Hat(this.constants_);
@@ -301,15 +294,9 @@ Blockly.blockRendering.RenderInfo.prototype.populateTopRow_ = function() {
     this.topRow.minHeight = this.constants_.TOP_ROW_MIN_HEIGHT;
   }
 
-  var rightSquareCorner = this.topRow.hasRightSquareCorner(this.block_);
-
-  if (rightSquareCorner) {
-    this.topRow.elements.push(
-        new Blockly.blockRendering.SquareCorner(this.constants_, 'right'));
-  } else {
-    this.topRow.elements.push(
-        new Blockly.blockRendering.RoundCorner(this.constants_, 'right'));
-  }
+  cornerClass = this.topRow.hasRightSquareCorner(this.block_) ?
+      Blockly.blockRendering.SquareCorner : Blockly.blockRendering.RoundCorner;
+  this.topRow.elements.push(new cornerClass(this.constants_, 'right'));
 };
 
 /**