diff --git a/core/block_render_svg.js b/core/block_render_svg.js
index 0b8998104..d8753a18f 100644
--- a/core/block_render_svg.js
+++ b/core/block_render_svg.js
@@ -907,7 +907,7 @@ Blockly.BlockSvg.prototype.renderInlineRow_ = function(pathObject, row, cursor,
   var steps = pathObject.steps;
   var highlightSteps = pathObject.highlightSteps;
 
-  for (var x = 0, input; input = row[x]; x++) {
+  for (var i = 0, input; input = row[i]; i++) {
     var fieldX = cursor.x;
     var fieldY = cursor.y;
     if (row.thicker) {
diff --git a/core/flyout_base.js b/core/flyout_base.js
index 61ffed7cb..b7897e7b1 100644
--- a/core/flyout_base.js
+++ b/core/flyout_base.js
@@ -404,7 +404,7 @@ Blockly.Flyout.prototype.hide = function() {
   }
   this.setVisible(false);
   // Delete all the event listeners.
-  for (var x = 0, listen; listen = this.listeners_[x]; x++) {
+  for (var i = 0, listen; listen = this.listeners_[i]; i++) {
     Blockly.unbindEvent_(listen);
   }
   this.listeners_.length = 0;
diff --git a/core/generator.js b/core/generator.js
index fc7471b7d..13cfc3358 100644
--- a/core/generator.js
+++ b/core/generator.js
@@ -96,7 +96,7 @@ Blockly.Generator.prototype.workspaceToCode = function(workspace) {
   var code = [];
   this.init(workspace);
   var blocks = workspace.getTopBlocks(true);
-  for (var x = 0, block; block = blocks[x]; x++) {
+  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/xml.js b/core/xml.js
index 158bd8e0c..d953c87e3 100644
--- a/core/xml.js
+++ b/core/xml.js
@@ -250,8 +250,8 @@ Blockly.Xml.cloneShadow_ = function(shadow) {
       while (node && !node.nextSibling) {
         textNode = node;
         node = node.parentNode;
-        if (textNode.nodeType == 3 && textNode.data.trim() == '' &&
-            node.firstChild != textNode) {
+        if (textNode.nodeType == Element.TEXT_NODE &&
+            textNode.data.trim() == '' && node.firstChild != textNode) {
           // Prune whitespace after a tag.
           Blockly.utils.removeNode(textNode);
         }
@@ -259,7 +259,8 @@ Blockly.Xml.cloneShadow_ = function(shadow) {
       if (node) {
         textNode = node;
         node = node.nextSibling;
-        if (textNode.nodeType == 3 && textNode.data.trim() == '') {
+        if (textNode.nodeType == Element.TEXT_NODE &&
+            textNode.data.trim() == '') {
           // Prune whitespace before a tag.
           Blockly.utils.removeNode(textNode);
         }
@@ -594,7 +595,7 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
 
   var blockChild = null;
   for (var i = 0, xmlChild; xmlChild = xmlBlock.childNodes[i]; i++) {
-    if (xmlChild.nodeType == 3) {
+    if (xmlChild.nodeType == Element.TEXT_NODE) {
       // Ignore any text at the <block> level.  It's all whitespace anyway.
       continue;
     }
@@ -604,7 +605,7 @@ Blockly.Xml.domToBlockHeadless_ = function(xmlBlock, workspace) {
     var childBlockElement = null;
     var childShadowElement = null;
     for (var j = 0, grandchild; grandchild = xmlChild.childNodes[j]; j++) {
-      if (grandchild.nodeType == 1) {
+      if (grandchild.nodeType == Element.ELEMENT_NODE) {
         if (grandchild.nodeName.toLowerCase() == 'block') {
           childBlockElement = /** @type {!Element} */ (grandchild);
         } else if (grandchild.nodeName.toLowerCase() == 'shadow') {