diff --git a/dom/apps/PermissionsTable.jsm b/dom/apps/PermissionsTable.jsm
index 1e42aa9a7b8..2306badf058 100644
--- a/dom/apps/PermissionsTable.jsm
+++ b/dom/apps/PermissionsTable.jsm
@@ -591,7 +591,7 @@ this.expandPermissions = function expandPermissions(aPermName, aAccess) {
 
     // Add the same suffix to each of the additions.
     if (tableEntry.additional) {
-      for each (let additional in tableEntry.additional) {
+      for (let additional of tableEntry.additional) {
         permArr = permArr.concat(appendAccessToPermName(additional, requestedSuffixes));
       }
     }
diff --git a/dom/base/test/chrome/title_window.xul b/dom/base/test/chrome/title_window.xul
index da2ee24b67a..5db180f8bf0 100644
--- a/dom/base/test/chrome/title_window.xul
+++ b/dom/base/test/chrome/title_window.xul
@@ -21,7 +21,7 @@
   <script type="application/javascript">
     <![CDATA[
     var imports = [ "SimpleTest", "is", "isnot", "ok" ];
-    for each (var name in imports) {
+    for (var name of imports) {
       window[name] = window.opener.wrappedJSObject[name];
     }
 
diff --git a/dom/base/test/file_XHR_anon.sjs b/dom/base/test/file_XHR_anon.sjs
index c6f400ec9bf..755c4cdf3e2 100644
--- a/dom/base/test/file_XHR_anon.sjs
+++ b/dom/base/test/file_XHR_anon.sjs
@@ -13,7 +13,7 @@ function handleRequest(request, response) {
     invalidHeaders.push("Authorization");
   }
 
-  for each (let header in invalidHeaders) {
+  for (let header of invalidHeaders) {
     if (request.hasHeader(header)) {
       response.setStatusLine(null, 500, "Server Error");
       headers[header.toLowerCase()] = request.getHeader(header);
diff --git a/dom/base/test/test_ipc_messagemanager_blob.html b/dom/base/test/test_ipc_messagemanager_blob.html
index 707d50a5bd5..c8872c93eeb 100644
--- a/dom/base/test/test_ipc_messagemanager_blob.html
+++ b/dom/base/test/test_ipc_messagemanager_blob.html
@@ -119,7 +119,7 @@
         mm.loadFrameScript("data:,(" + childFrameScript.toString() + ")();",
                            false);
 
-        for each (let message in messages) {
+        for (let message of messages) {
           mm.sendAsyncMessage("test:ipcClonedMessage", message);
         }
       });
diff --git a/dom/browser-element/BrowserElementPromptService.jsm b/dom/browser-element/BrowserElementPromptService.jsm
index 512950a327d..7686ea3ca88 100644
--- a/dom/browser-element/BrowserElementPromptService.jsm
+++ b/dom/browser-element/BrowserElementPromptService.jsm
@@ -338,7 +338,7 @@ BrowserElementAuthPrompt.prototype = {
         prompt.authInfo.password = password;
       }
 
-      for each (let consumer in prompt.consumers) {
+      for (let consumer of prompt.consumers) {
         if (!consumer.callback) {
           // Not having a callback means that consumer didn't provide it
           // or canceled the notification.
diff --git a/dom/events/test/test_bug336682_2.xul b/dom/events/test/test_bug336682_2.xul
index bd7c591b68f..303348c2ec5 100644
--- a/dom/events/test/test_bug336682_2.xul
+++ b/dom/events/test/test_bug336682_2.xul
@@ -38,7 +38,7 @@ addLoadEvent(function() {
     }
   }
 
-  for each(var event in ["online", "offline"]) {
+  for (var event of ["online", "offline"]) {
     document.documentElement.addEventListener(
       event,
       makeHandler("document.body.addEventListener('%1', ..., false)",
diff --git a/dom/events/test/test_bug822898.html b/dom/events/test/test_bug822898.html
index 8c3f1312d5e..bb34f26d96d 100644
--- a/dom/events/test/test_bug822898.html
+++ b/dom/events/test/test_bug822898.html
@@ -67,12 +67,12 @@ function createTestEventValue(name) {
       is(ev.pointerId, pointerId, "Correct pointerId");
     }
 
-    for each (let target in [document, window, testTarget, parent])
+    for (let target of [document, window, testTarget, parent])
       target.addEventListener(name, check, false);
 
     testTarget.dispatchEvent(event);
 
-    for each (let target in [document, window, testTarget, parent])
+    for (let target of [document, window, testTarget, parent])
       target.removeEventListener(name, check, false);
 
 
diff --git a/dom/html/test/test_checked.html b/dom/html/test/test_checked.html
index afc7f3af0ff..9d40a6ded2a 100644
--- a/dom/html/test/test_checked.html
+++ b/dom/html/test/test_checked.html
@@ -34,7 +34,7 @@ var group2;
 var group3;
 
 var tags = ["input", "menuitem"];
-for each (let tag in tags) {
+for (let tag of tags) {
 
 function bounce(node) {
   let n = node.nextSibling;
@@ -46,7 +46,7 @@ function bounce(node) {
 var createdNodes = [];
 
 function cleanup() {
-  for each (let node in createdNodes) {
+  for (let node of createdNodes) {
     if (node.parentNode) {
       node.parentNode.removeChild(node);
     }
@@ -79,7 +79,7 @@ var types = ['c', 'r'];
 
 // First make sure that setting .checked makes .defaultChecked changes no
 // longer affect .checked.
-for each (let type in types) {
+for (let type of types) {
   let n = createNode(type, '', false);
   is(n.defaultChecked, false, "Bogus defaultChecked on " + typeMapper[type]);
   is(n.checked, false, "Bogus checked on " + typeMapper[type]);
@@ -109,7 +109,7 @@ cleanup();
 
 // Now check that bouncing a control that's the only one of its kind has no
 // effect
-for each (let type in types) {
+for (let type of types) {
   let n = createNode(type, 'test1', true);
   $(tag == "input" ? "f1" : "m1").appendChild(n);
   n.checked = false;
diff --git a/dom/mobilemessage/gonk/MmsService.js b/dom/mobilemessage/gonk/MmsService.js
index 1ae7db7c48c..707302ba812 100644
--- a/dom/mobilemessage/gonk/MmsService.js
+++ b/dom/mobilemessage/gonk/MmsService.js
@@ -1647,7 +1647,7 @@ MmsService.prototype = {
 
     savable.receivers = [];
     // We don't have Bcc in recevied MMS message.
-    for each (let type in ["cc", "to"]) {
+    for (let type of ["cc", "to"]) {
       if (intermediate.headers[type]) {
         if (intermediate.headers[type] instanceof Array) {
           for (let index in intermediate.headers[type]) {
diff --git a/dom/mobilemessage/gonk/MobileMessageDB.jsm b/dom/mobilemessage/gonk/MobileMessageDB.jsm
index fd39bd2208b..4c21364eed5 100644
--- a/dom/mobilemessage/gonk/MobileMessageDB.jsm
+++ b/dom/mobilemessage/gonk/MobileMessageDB.jsm
@@ -673,7 +673,7 @@ MobileMessageDB.prototype = {
         stores = txn.objectStore(storeNames[0]);
       } else {
         stores = [];
-        for each (let storeName in storeNames) {
+        for (let storeName of storeNames) {
           if (DEBUG) debug("Retrieving object store " + storeName);
           stores.push(txn.objectStore(storeName));
         }
@@ -1460,7 +1460,7 @@ MobileMessageDB.prototype = {
               let timestamp = messageRecord.timestamp;
               // Setup participantIdsIndex.
               messageRecord.participantIdsIndex = [];
-              for each (let id in participantIds) {
+              for (let id of participantIds) {
                 messageRecord.participantIdsIndex.push([id, timestamp]);
               }
               if (threadRecord) {
@@ -2857,7 +2857,7 @@ MobileMessageDB.prototype = {
         aMessageRecord.threadIdIndex = [threadId, timestamp];
         // Setup participantIdsIndex.
         aMessageRecord.participantIdsIndex = [];
-        for each (let id in participantIds) {
+        for (let id of participantIds) {
           aMessageRecord.participantIdsIndex.push([id, timestamp]);
         }
 
diff --git a/dom/mobilemessage/tests/marionette/test_mmdb_upgradeSchema_22.js b/dom/mobilemessage/tests/marionette/test_mmdb_upgradeSchema_22.js
index 704bb4a0e36..f6476415878 100644
--- a/dom/mobilemessage/tests/marionette/test_mmdb_upgradeSchema_22.js
+++ b/dom/mobilemessage/tests/marionette/test_mmdb_upgradeSchema_22.js
@@ -171,7 +171,7 @@ var LEGACY = {
         aMessageRecord.threadIdIndex = [threadId, timestamp];
         // Setup participantIdsIndex.
         aMessageRecord.participantIdsIndex = [];
-        for each (let id in participantIds) {
+        for (let id of participantIds) {
           aMessageRecord.participantIdsIndex.push([id, timestamp]);
         }
 
diff --git a/dom/payment/Payment.jsm b/dom/payment/Payment.jsm
index be0dd042317..df226b72646 100644
--- a/dom/payment/Payment.jsm
+++ b/dom/payment/Payment.jsm
@@ -45,7 +45,7 @@ var PaymentManager =  {
       }
     } catch(e) {}
 
-    for each (let msgname in PAYMENT_IPC_MSG_NAMES) {
+    for (let msgname of PAYMENT_IPC_MSG_NAMES) {
       ppmm.addMessageListener(msgname, this);
     }
 
@@ -401,7 +401,7 @@ var PaymentManager =  {
 
   observe: function observe(subject, topic, data) {
     if (topic == "xpcom-shutdown") {
-      for each (let msgname in PAYMENT_IPC_MSG_NAMES) {
+      for (let msgname of PAYMENT_IPC_MSG_NAMES) {
         ppmm.removeMessageListener(msgname, this);
       }
       this.registeredProviders = null;
diff --git a/dom/svg/test/test_SVGxxxListIndexing.xhtml b/dom/svg/test/test_SVGxxxListIndexing.xhtml
index 10f6f1ba57f..31544b23dd4 100644
--- a/dom/svg/test/test_SVGxxxListIndexing.xhtml
+++ b/dom/svg/test/test_SVGxxxListIndexing.xhtml
@@ -79,13 +79,13 @@ var tests = [
                 { values: "foo bar baz qux", length: 4 } ] }
 ];
 
-for each (let test in tests) {
+for (let test of tests) {
   let list = test.element;
-  for each (let property in test.listProperty.split(".")) {
+  for (let property of test.listProperty.split(".")) {
     list = list[property];
   }
 
-  for each (let subtest in test.subtests) {
+  for (let subtest of test.subtests) {
     if (subtest.values) {
       test.element.setAttribute(test.attribute, subtest.values);
     }
diff --git a/dom/svg/test/test_pathAnimInterpolation.xhtml b/dom/svg/test/test_pathAnimInterpolation.xhtml
index 66b89f09f1c..5269db1ca9e 100644
--- a/dom/svg/test/test_pathAnimInterpolation.xhtml
+++ b/dom/svg/test/test_pathAnimInterpolation.xhtml
@@ -267,7 +267,7 @@ function isValidInterpolation(aFromType, aToType)
 // Runs the test.
 function run()
 {
-  for each (let additive in [false, true]) {
+  for (let additive of [false, true]) {
     let indexOfExpectedArguments = additive ? 3 : 2;
 
     // Add subtests for each combination of prefix and suffix, and additive
@@ -279,7 +279,7 @@ function run()
           toArguments = suffixEntry[1],
           expectedArguments = suffixEntry[indexOfExpectedArguments];
 
-      for each (let prefixEntry in gPrefixes) {
+      for (let prefixEntry of gPrefixes) {
         let [prefixLength, prefix] = prefixEntry;
         addTest(prefixLength, prefix, fromType, fromArguments,
 	        toType, toArguments, toType, expectedArguments, additive);
@@ -298,9 +298,9 @@ function run()
 	    "a", [60, 70, 80, 1, 0, 90, 100], additive);
 
     // Test all pairs of segment types that cannot be interpolated between.
-    for each (let fromType in gTypes) {
+    for (let fromType of gTypes) {
       let fromArguments = generatePathSegmentArguments(fromType, 0);
-      for each (let toType in gTypes) {
+      for (let toType of gTypes) {
         if (!isValidInterpolation(fromType, toType)) {
           let toArguments = generatePathSegmentArguments(toType, 1000);
           addTest(1, "M100,100", fromType, fromArguments,
@@ -314,7 +314,7 @@ function run()
   gSVG.setCurrentTime(4);
 
   // Inspect the results of each subtest.
-  for each (let test in gTests) {
+  for (let test of gTests) {
     let list = test.element.animatedPathSegList;
     is(list.numberOfItems, test.prefixLength + 1,
        "Length of animatedPathSegList for interpolation " +
diff --git a/dom/system/gonk/NetworkManager.js b/dom/system/gonk/NetworkManager.js
index ab5ed1904ec..4a63a01e7c4 100644
--- a/dom/system/gonk/NetworkManager.js
+++ b/dom/system/gonk/NetworkManager.js
@@ -236,7 +236,8 @@ NetworkManager.prototype = {
         let excludeFota = aMsg.json.excludeFota;
         let interfaces = [];
 
-        for each (let network in this.networkInterfaces) {
+        for (let key in this.networkInterfaces) {
+          let network = this.networkInterfaces[key];
           let i = network.info;
           if ((i.type == Ci.nsINetworkInfo.NETWORK_TYPE_MOBILE_MMS && excludeMms) ||
               (i.type == Ci.nsINetworkInfo.NETWORK_TYPE_MOBILE_SUPL && excludeSupl) ||
@@ -825,7 +826,8 @@ NetworkManager.prototype = {
     this._activeNetwork = null;
     let anyConnected = false;
 
-    for each (let network in this.networkInterfaces) {
+    for (let key in this.networkInterfaces) {
+      let network = this.networkInterfaces[key];
       if (network.info.state != Ci.nsINetworkInfo.NETWORK_STATE_CONNECTED) {
         continue;
       }
diff --git a/dom/system/gonk/TetheringService.js b/dom/system/gonk/TetheringService.js
index 4197c7c24ef..c5c4781806c 100644
--- a/dom/system/gonk/TetheringService.js
+++ b/dom/system/gonk/TetheringService.js
@@ -363,7 +363,8 @@ TetheringService.prototype = {
   },
 
   getNetworkInfo: function(aType, aServiceId) {
-    for each (let networkInfo in gNetworkManager.allNetworkInfo) {
+    for (let networkId in gNetworkManager.allNetworkInfo) {
+      let networkInfo = gNetworkManager.allNetworkInfo[networkId];
       if (networkInfo.type == aType) {
         try {
           if (networkInfo instanceof Ci.nsIRilNetworkInfo) {
diff --git a/dom/system/gonk/ril_worker.js b/dom/system/gonk/ril_worker.js
index 862a408c996..307bfde631c 100644
--- a/dom/system/gonk/ril_worker.js
+++ b/dom/system/gonk/ril_worker.js
@@ -3786,7 +3786,8 @@ RilObject.prototype = {
     }
 
     let list = null;
-    for each (let ll in usedCellBroadcastConfigs) {
+    for (let key in usedCellBroadcastConfigs) {
+      let ll = usedCellBroadcastConfigs[key];
       if (ll == null) {
         continue;
       }
diff --git a/dom/tv/TVSimulatorService.js b/dom/tv/TVSimulatorService.js
index 0f79c3e01c4..785e9d8d223 100644
--- a/dom/tv/TVSimulatorService.js
+++ b/dom/tv/TVSimulatorService.js
@@ -141,7 +141,7 @@ TVSimulatorService.prototype = {
     this._internalTuners = new Map();
 
     // TVTunerData
-    for each (let tunerData in settingsObj.tuners) {
+    for (let tunerData of settingsObj.tuners) {
       let tuner = Cc["@mozilla.org/tv/tvtunerdata;1"]
                     .createInstance(Ci.nsITVTunerData);
       tuner.id = tunerData.id;
@@ -156,11 +156,11 @@ TVSimulatorService.prototype = {
       };
 
       // TVSource
-      for each (let sourceData in tunerData.sources) {
+      for (let sourceData of tunerData.sources) {
         wrapTunerData.sourceType = sourceData.type;
 
         // TVChannel
-        for each (let channelData in sourceData.channels) {
+        for (let channelData of sourceData.channels) {
           let channel = Cc["@mozilla.org/tv/tvchanneldata;1"]
                           .createInstance(Ci.nsITVChannelData);
           channel.networkId         = channelData.networkId;
@@ -179,7 +179,7 @@ TVSimulatorService.prototype = {
           };
 
           // TVProgram
-          for each (let programData in channelData.programs) {
+          for (let programData of channelData.programs) {
             let program = Cc["@mozilla.org/tv/tvprogramdata;1"]
                             .createInstance(Ci.nsITVProgramData);
             program.eventId     = programData.eventId;
@@ -386,7 +386,7 @@ TVSimulatorService.prototype = {
       return Cr.NS_ERROR_INVALID_ARG;
     }
 
-    for each (let program in wrapChannelData.programs) {
+    for (let program of wrapChannelData.programs) {
       programArray.appendElement(program, false);
     }
 
@@ -461,7 +461,7 @@ TVSimulatorService.prototype = {
 
   _validateTuners: function TVSimValidateTuners(aTunersObject) {
     let tunerIds = new Array();
-    for each (let tuner in aTunersObject) {
+    for (let tuner of aTunersObject) {
       if (!tuner.id ||
           !tuner.supportedType ||
           !tuner.supportedType.length ||
@@ -480,7 +480,7 @@ TVSimulatorService.prototype = {
   },
 
   _validateSources: function TVSimValidateSources(aSourcesObject) {
-    for each (let source in aSourcesObject) {
+    for (let source of aSourcesObject) {
       if (!source.type ||
           !TV_SOURCE_TYPES.includes(source.type)) {
         debug("invalid source data.");
@@ -496,7 +496,7 @@ TVSimulatorService.prototype = {
 
   _validateChannels: function TVSimValidateChannels(aChannelsObject) {
     let channelNumbers = new Array();
-    for each (let channel in aChannelsObject) {
+    for (let channel of aChannelsObject) {
       if (!channel.networkId ||
           !channel.transportStreamId ||
           !channel.serviceId ||
@@ -519,7 +519,7 @@ TVSimulatorService.prototype = {
 
   _validatePrograms: function TVSimValidatePrograms(aProgramsObject) {
     let eventIds = new Array();
-    for each (let program in aProgramsObject) {
+    for (let program of aProgramsObject) {
       if (!program.eventId ||
           eventIds.includes(program.eventId) ||
           !program.title ||
diff --git a/dom/voicemail/test/marionette/head.js b/dom/voicemail/test/marionette/head.js
index 69aeb2be522..1ccf09b37ed 100644
--- a/dom/voicemail/test/marionette/head.js
+++ b/dom/voicemail/test/marionette/head.js
@@ -128,7 +128,7 @@ var PDUBuilder = {
     let headerLength = 0;
     this.buf = "";
     if (options.headers) {
-      for each (let header in options.headers) {
+      for (let header of options.headers) {
         headerLength += 2; // id + length octets
         if (header.octets) {
           headerLength += header.octets.length;
@@ -149,12 +149,12 @@ var PDUBuilder = {
     if (options.headers) {
       this.writeHexOctet(headerLength);
 
-      for each (let header in options.headers) {
+      for (let header of options.headers) {
         this.writeHexOctet(header.id);
         this.writeHexOctet(header.length);
 
         if (header.octets) {
-          for each (let octet in header.octets) {
+          for (let octet of header.octets) {
             this.writeHexOctet(octet);
           }
         }
diff --git a/dom/wifi/WifiWorker.js b/dom/wifi/WifiWorker.js
index 5e7128c52ba..243ba8b9787 100644
--- a/dom/wifi/WifiWorker.js
+++ b/dom/wifi/WifiWorker.js
@@ -2608,7 +2608,8 @@ WifiWorker.prototype = {
   // connect to which ever network it thinks is best, so when we select the
   // proper network (or fail to), we need to re-enable the rest.
   _enableAllNetworks: function() {
-    for each (let net in this.configuredNetworks) {
+    for (let key in this.configuredNetworks) {
+      let net = this.configuredNetworks[key];
       WifiManager.enableNetwork(net.netId, false, function(ok) {
         net.disabled = ok ? 1 : 0;
       });
diff --git a/dom/workers/test/extensions/bootstrap/bootstrap.js b/dom/workers/test/extensions/bootstrap/bootstrap.js
index d0064c4bbe5..f79934d285f 100644
--- a/dom/workers/test/extensions/bootstrap/bootstrap.js
+++ b/dom/workers/test/extensions/bootstrap/bootstrap.js
@@ -11,7 +11,7 @@ Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 function testForExpectedSymbols(stage, data) {
   const expectedSymbols = [ "Worker", "ChromeWorker" ];
-  for each (var symbol in expectedSymbols) {
+  for (var symbol of expectedSymbols) {
     Services.prefs.setBoolPref("workertest.bootstrap." + stage + "." + symbol,
                                symbol in this);
   }
diff --git a/dom/workers/test/test_extensionBootstrap.xul b/dom/workers/test/test_extensionBootstrap.xul
index 33ca229e279..18bdde1d3ed 100644
--- a/dom/workers/test/test_extensionBootstrap.xul
+++ b/dom/workers/test/test_extensionBootstrap.xul
@@ -31,8 +31,8 @@
             const stages = [ "install", "startup", "shutdown", "uninstall" ];
             const symbols = [ "Worker", "ChromeWorker" ];
 
-            for each (var stage in stages) {
-              for each (var symbol in symbols) {
+            for (var stage of stages) {
+              for (var symbol of symbols) {
                 is(Services.prefs.getBoolPref("workertest.bootstrap." + stage +
                                               "." + symbol),
                    true,