MD Settings: Eliminate use of ES6 for Chrome OS

chrome/browser/resources/settings/internet_page/network_nameservers.js

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * @fileoverview Polymer element for displaying network nameserver options.
  */
 Polymer({
   is: 'network-nameservers',
 
@@ skipping 92 matching lines @@
   },
 
   /**
    * @param {string} nameserversType
    * @param {!Array<string>} nameservers
    * @private
    */
   setNameservers_: function(nameserversType, nameservers) {
     if (nameserversType == 'custom') {
       // Add empty entries for unset custom nameservers.
-      for (let i = nameservers.length; i < this.MAX_NAMESERVERS; ++i)
+      for (var i = nameservers.length; i < this.MAX_NAMESERVERS; ++i)
         nameservers[i] = '';
     }
     this.nameservers_ = nameservers;
     // Set nameserversType_ after dom-repeat has been stamped.
     this.async(function() {
       this.nameserversType_ = nameserversType;
     }.bind(this));
   },
 
   /**
@@ skipping 22 matching lines @@
 
   /**
    * Event triggered when the selected type changes. Updates nameservers and
    * sends the change value if necessary.
    * @param {!Event} event
    * @private
    */
   onTypeChange_: function(event) {
     if (this.nameserversType_ == 'custom')
       this.savedNameservers_ = this.nameservers_;
-    let target = /** @type {!HTMLSelectElement} */ (event.target);
-    let type = target.value;
+    var target = /** @type {!HTMLSelectElement} */ (event.target);
+    var type = target.value;
     this.nameserversType_ = type;
     if (type == 'custom') {
       // Restore the saved nameservers.
       this.setNameservers_(type, this.savedNameservers_);
       // Only send custom nameservers if they are not empty.
       if (this.savedNameservers_.length == 0)
         return;
     }
     this.sendNameServers_();
   },
@@ skipping 12 matching lines @@
   },
 
   /**
    * Sends the current nameservers type (for automatic) or value.
    * @private
    */
   sendNameServers_: function() {
     var type = this.nameserversType_;
 
     if (type == 'custom') {
-      let nameservers = [];
-      for (let i = 0; i < this.MAX_NAMESERVERS; ++i) {
-        let id = 'nameserver' + i;
-        let nameserverInput = this.$$('#' + id);
-        let nameserver = '';
+      var nameservers = [];

[dpapad, 2017/01/23 19:12:54]

Nit: You can use Array#map instead.

var nameservers = this.MAX_NAMESERVERS.map(function(i) {
  var nameserver = '';
  ...
  return nameserver;
}.bind(this));

[stevenjb, 2017/01/24 02:02:04]

MAX_NAMESERVERS is a number, not an Array. But I can pre-allocate the array and
greatly simplify this (very early JS) so I will do that.

+      for (var i = 0; i < this.MAX_NAMESERVERS; ++i) {
+        var id = 'nameserver' + i;
+        var nameserverInput = this.$$('#' + id);
+        var nameserver = '';
         if (nameserverInput)
           nameserver = this.$$('#' + id).value;
         nameservers.push(nameserver);
       }
       this.fire('nameservers-change', {
         field: 'NameServers',
         value: nameservers,
       });
     } else if (type == 'google') {
-      let nameservers = this.GOOGLE_NAMESERVERS;
       this.fire('nameservers-change', {
         field: 'NameServers',
-        value: nameservers,
+        value: this.GOOGLE_NAMESERVERS,
       });
     } else {
       // automatic
       this.fire('nameservers-change', {
         field: 'NameServersConfigType',
         value: CrOnc.IPConfigType.DHCP,
       });
     }
   },
 });