diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 652b8e2..6bb10d9 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Provides Ajax page updating via jQuery $.ajax (Asynchronous JavaScript and XML).
  *
diff --git a/core/misc/authorize.js b/core/misc/authorize.js
index d522a5b..e7858d6 100644
--- a/core/misc/authorize.js
+++ b/core/misc/authorize.js
@@ -7,6 +7,8 @@
 
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.authorizeFileTransferForm = {
   attach: function(context) {
     $('#edit-connection-settings-authorize-filetransfer-default').change(function() {
diff --git a/core/misc/autocomplete.js b/core/misc/autocomplete.js
index 122f05d..8945c70 100644
--- a/core/misc/autocomplete.js
+++ b/core/misc/autocomplete.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Attaches the autocomplete behavior to all required fields.
  */
diff --git a/core/misc/batch.js b/core/misc/batch.js
index fee71a5..0e2cb1c 100644
--- a/core/misc/batch.js
+++ b/core/misc/batch.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Attaches the batch behavior to progress bars.
  */
diff --git a/core/misc/collapse.js b/core/misc/collapse.js
index 1a98dc0..408152c 100644
--- a/core/misc/collapse.js
+++ b/core/misc/collapse.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Toggle the visibility of a fieldset using smooth animations.
  */
diff --git a/core/misc/drupal.js b/core/misc/drupal.js
index 83b0884..ca132ff 100644
--- a/core/misc/drupal.js
+++ b/core/misc/drupal.js
@@ -6,6 +6,8 @@ jQuery.noConflict();
 
 (function ($) {
 
+"use strict";
+
 /**
  * Attach all registered behaviors to a page element.
  *
diff --git a/core/misc/form.js b/core/misc/form.js
index 259b84e..8c5d2ec 100644
--- a/core/misc/form.js
+++ b/core/misc/form.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Retrieves the summary for the first element.
  */
diff --git a/core/misc/machine-name.js b/core/misc/machine-name.js
index ced8c4b..bbdba31 100644
--- a/core/misc/machine-name.js
+++ b/core/misc/machine-name.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Attach the machine-readable name form element behavior.
  */
diff --git a/core/misc/progress.js b/core/misc/progress.js
index 822666a..0d3aab1 100644
--- a/core/misc/progress.js
+++ b/core/misc/progress.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * A progressbar object. Initialized with the given id. Must be inserted into
  * the DOM afterwards through progressBar.element.
diff --git a/core/misc/states.js b/core/misc/states.js
index 3c17efc..9b15fd4 100644
--- a/core/misc/states.js
+++ b/core/misc/states.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * The base States namespace.
  *
diff --git a/core/misc/tabledrag.js b/core/misc/tabledrag.js
index da10a0e..d756f49 100644
--- a/core/misc/tabledrag.js
+++ b/core/misc/tabledrag.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Drag and drop table rows with field manipulation.
  *
diff --git a/core/misc/tableheader.js b/core/misc/tableheader.js
index 543862c..de552e7 100644
--- a/core/misc/tableheader.js
+++ b/core/misc/tableheader.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Attaches sticky table headers.
  */
diff --git a/core/misc/tableselect.js b/core/misc/tableselect.js
index fee63a9..57ddc74 100644
--- a/core/misc/tableselect.js
+++ b/core/misc/tableselect.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.tableSelect = {
   attach: function (context, settings) {
     // Select the inner-most table in case of nested tables.
diff --git a/core/misc/timezone.js b/core/misc/timezone.js
index 5449730..27bc4e7 100644
--- a/core/misc/timezone.js
+++ b/core/misc/timezone.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Set the client's system time zone as default values of form fields.
  */
diff --git a/core/misc/vertical-tabs.js b/core/misc/vertical-tabs.js
index 14d0660..25caf0c 100644
--- a/core/misc/vertical-tabs.js
+++ b/core/misc/vertical-tabs.js
@@ -1,6 +1,7 @@
-
 (function ($) {
 
+"use strict";
+
 /**
  * This script transforms a set of fieldsets into a stack of vertical
  * tabs. Another tab pane can be selected by clicking on the respective
diff --git a/core/modules/block/block.js b/core/modules/block/block.js
index 72b5673..70a185f 100644
--- a/core/modules/block/block.js
+++ b/core/modules/block/block.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Provide the summary information for the block settings vertical tabs.
  */
@@ -83,7 +85,7 @@ Drupal.behaviors.blockDrag = {
 
     // Add a handler so when a row is dropped, update fields dropped into new regions.
     tableDrag.onDrop = function () {
-      dragObject = this;
+      var dragObject = this;
       // Use "region-message" row instead of "region" row because
       // "region-{region_name}-message" is less prone to regexp match errors.
       var regionRow = $(dragObject.rowObject.element).prevAll('tr.region-message').get(0);
diff --git a/core/modules/book/book.js b/core/modules/book/book.js
index 075f33b..2bd0fd3 100644
--- a/core/modules/book/book.js
+++ b/core/modules/book/book.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.bookFieldsetSummaries = {
   attach: function (context) {
     $('fieldset.book-outline-form', context).drupalSetSummary(function (context) {
diff --git a/core/modules/color/color.js b/core/modules/color/color.js
index ae0019e..8bc624c 100644
--- a/core/modules/color/color.js
+++ b/core/modules/color/color.js
@@ -5,6 +5,8 @@
 
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.color = {
   attach: function (context, settings) {
     var i, j, colors, field_name;
diff --git a/core/modules/color/preview.js b/core/modules/color/preview.js
index 67eef0b..f3461aa 100644
--- a/core/modules/color/preview.js
+++ b/core/modules/color/preview.js
@@ -4,6 +4,9 @@
  */
 
 (function ($) {
+
+  "use strict";
+
   Drupal.color = {
     callback: function(context, settings, form, farb, height, width) {
       // Solid background.
diff --git a/core/modules/comment/comment-node-form.js b/core/modules/comment/comment-node-form.js
index e46f05e..1a84c0a 100644
--- a/core/modules/comment/comment-node-form.js
+++ b/core/modules/comment/comment-node-form.js
@@ -5,6 +5,8 @@
 
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.commentFieldsetSummaries = {
   attach: function (context) {
     $('fieldset.comment-node-settings-form', context).drupalSetSummary(function (context) {
diff --git a/core/modules/contextual/contextual.js b/core/modules/contextual/contextual.js
index 2744acb..a780b3c 100644
--- a/core/modules/contextual/contextual.js
+++ b/core/modules/contextual/contextual.js
@@ -5,6 +5,8 @@
 
 (function ($) {
 
+"use strict";
+
 Drupal.contextualLinks = Drupal.contextualLinks || {};
 
 /**
diff --git a/core/modules/dashboard/dashboard.js b/core/modules/dashboard/dashboard.js
index ca2a3b5..8bf691b 100644
--- a/core/modules/dashboard/dashboard.js
+++ b/core/modules/dashboard/dashboard.js
@@ -5,6 +5,8 @@
 
 (function ($) {
 
+"use strict";
+
 /**
  * Implements Drupal.behaviors for the Dashboard module.
  */
diff --git a/core/modules/field/modules/text/text.js b/core/modules/field/modules/text/text.js
index f3ae894..334fe73 100644
--- a/core/modules/field/modules/text/text.js
+++ b/core/modules/field/modules/text/text.js
@@ -1,6 +1,7 @@
-
 (function ($) {
 
+"use strict";
+
 /**
  * Auto-hide summary textarea if empty and show hide and unhide links.
  */
diff --git a/core/modules/field_ui/field_ui.js b/core/modules/field_ui/field_ui.js
index 7359595..3746f8b 100644
--- a/core/modules/field_ui/field_ui.js
+++ b/core/modules/field_ui/field_ui.js
@@ -5,6 +5,8 @@
  
 (function($) {
 
+"use strict";
+
 Drupal.behaviors.fieldUIFieldOverview = {
   attach: function (context, settings) {
     $('table#field-overview', context).once('field-overview', function () {
@@ -174,7 +176,7 @@ Drupal.fieldUIOverview = {
 
       if (region != rowHandler.region) {
         // Let the row handler deal with the region change.
-        refreshRows = rowHandler.regionChange(region);
+        var refreshRows = rowHandler.regionChange(region);
         // Update the row region.
         rowHandler.region = region;
         // Ajax-update the rows.
diff --git a/core/modules/file/file.js b/core/modules/file/file.js
index 8113170..416cfc7 100644
--- a/core/modules/file/file.js
+++ b/core/modules/file/file.js
@@ -10,6 +10,8 @@
 
 (function ($) {
 
+"use strict";
+
 /**
  * Attach behaviors to managed file element upload fields.
  */
diff --git a/core/modules/filter/filter.admin.js b/core/modules/filter/filter.admin.js
index 3bc6233..6e3084f 100644
--- a/core/modules/filter/filter.admin.js
+++ b/core/modules/filter/filter.admin.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.filterStatus = {
   attach: function (context, settings) {
     $('#filters-status-wrapper input.form-checkbox', context).once('filter-status', function () {
diff --git a/core/modules/filter/filter.js b/core/modules/filter/filter.js
index c286159..d7c6ce1 100644
--- a/core/modules/filter/filter.js
+++ b/core/modules/filter/filter.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Automatically display the guidelines of the selected text format.
  */
diff --git a/core/modules/locale/locale.datepicker.js b/core/modules/locale/locale.datepicker.js
index 81f1e17..024c1e2 100644
--- a/core/modules/locale/locale.datepicker.js
+++ b/core/modules/locale/locale.datepicker.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 $.datepicker.regional['drupal-locale'] = {
   closeText: Drupal.t('Done'),
   prevText: Drupal.t('Prev'),
diff --git a/core/modules/menu/menu.admin.js b/core/modules/menu/menu.admin.js
index 4fa094e..690ba4a 100644
--- a/core/modules/menu/menu.admin.js
+++ b/core/modules/menu/menu.admin.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.menuChangeParentItems = {
   attach: function (context, settings) {
     $('fieldset#edit-menu input').each(function () {
diff --git a/core/modules/menu/menu.js b/core/modules/menu/menu.js
index ff4ef1e..f7a2d1c 100644
--- a/core/modules/menu/menu.js
+++ b/core/modules/menu/menu.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.menuFieldsetSummaries = {
   attach: function (context) {
     $('fieldset.menu-link-form', context).drupalSetSummary(function (context) {
diff --git a/core/modules/node/content_types.js b/core/modules/node/content_types.js
index 0031c32..3da11f9 100644
--- a/core/modules/node/content_types.js
+++ b/core/modules/node/content_types.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.contentTypes = {
   attach: function (context) {
     // Provide the vertical tab summaries.
diff --git a/core/modules/node/node.js b/core/modules/node/node.js
index ebf68eb..fcc4cef 100644
--- a/core/modules/node/node.js
+++ b/core/modules/node/node.js
@@ -1,6 +1,7 @@
-
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.nodeFieldsetSummaries = {
   attach: function (context) {
     $('fieldset.node-form-revision-information', context).drupalSetSummary(function (context) {
diff --git a/core/modules/openid/openid.js b/core/modules/openid/openid.js
index 4a09e5a..0cf162c 100644
--- a/core/modules/openid/openid.js
+++ b/core/modules/openid/openid.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.openid = {
   attach: function (context) {
     var loginElements = $('.form-item-name, .form-item-pass, li.openid-link');
diff --git a/core/modules/overlay/overlay-child.js b/core/modules/overlay/overlay-child.js
index e78e383..cc387db 100644
--- a/core/modules/overlay/overlay-child.js
+++ b/core/modules/overlay/overlay-child.js
@@ -1,6 +1,7 @@
-
 (function ($) {
 
+"use strict";
+
 /**
  * Attach the child dialog behavior to new content.
  */
diff --git a/core/modules/overlay/overlay-parent.js b/core/modules/overlay/overlay-parent.js
index 2e3b4f9..ff2f512 100644
--- a/core/modules/overlay/overlay-parent.js
+++ b/core/modules/overlay/overlay-parent.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Open the overlay, or load content into it, when an admin link is clicked.
  */
diff --git a/core/modules/path/path.js b/core/modules/path/path.js
index fcc0acc..9fc821b 100644
--- a/core/modules/path/path.js
+++ b/core/modules/path/path.js
@@ -1,6 +1,8 @@
 
 (function ($) {
 
+"use strict";
+
 Drupal.behaviors.pathFieldsetSummaries = {
   attach: function (context) {
     $('fieldset.path-form', context).drupalSetSummary(function (context) {
diff --git a/core/modules/shortcut/shortcut.admin.js b/core/modules/shortcut/shortcut.admin.js
index 5554e5a..7d552c9 100644
--- a/core/modules/shortcut/shortcut.admin.js
+++ b/core/modules/shortcut/shortcut.admin.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Handle the concept of a fixed number of slots.
  *
diff --git a/core/modules/simpletest/simpletest.js b/core/modules/simpletest/simpletest.js
index 9cab261..23cb2e4 100644
--- a/core/modules/simpletest/simpletest.js
+++ b/core/modules/simpletest/simpletest.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Add the cool table collapsing on the testing overview page.
  */
@@ -8,7 +10,7 @@ Drupal.behaviors.simpleTestMenuCollapse = {
     var timeout = null;
     // Adds expand-collapse functionality.
     $('div.simpletest-image').each(function () {
-      direction = settings.simpleTest[$(this).attr('id')].imageDirection;
+      var direction = settings.simpleTest[$(this).attr('id')].imageDirection;
       $(this).html(settings.simpleTest.images[direction]);
     });
 
diff --git a/core/modules/system/system.cron.js b/core/modules/system/system.cron.js
index af17dab..a35a914 100644
--- a/core/modules/system/system.cron.js
+++ b/core/modules/system/system.cron.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Checks to see if the cron should be automatically run.
  */
diff --git a/core/modules/system/system.js b/core/modules/system/system.js
index f4bdc6d..732f671 100644
--- a/core/modules/system/system.js
+++ b/core/modules/system/system.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Show/hide the 'Email site administrator when updates are available' checkbox
  * on the install page.
diff --git a/core/modules/taxonomy/taxonomy.js b/core/modules/taxonomy/taxonomy.js
index 1a0c790..6cf206a 100644
--- a/core/modules/taxonomy/taxonomy.js
+++ b/core/modules/taxonomy/taxonomy.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Move a block in the blocks table from one region to another via select list.
  *
diff --git a/core/modules/toolbar/toolbar.js b/core/modules/toolbar/toolbar.js
index d50f205..b0c502e 100644
--- a/core/modules/toolbar/toolbar.js
+++ b/core/modules/toolbar/toolbar.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 Drupal.toolbar = Drupal.toolbar || {};
 
 /**
diff --git a/core/modules/user/user.js b/core/modules/user/user.js
index 042668d..0acd5cc 100644
--- a/core/modules/user/user.js
+++ b/core/modules/user/user.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Attach handlers to evaluate the strength of any password fields and to check
  * that its confirmation is correct.
@@ -155,6 +157,7 @@ Drupal.evaluatePasswordStrength = function (password, translate) {
     strength = 5;
   }
 
+  var indicatorText;
   // Based on the strength, work out what text should be shown by the password strength meter.
   if (strength < 60) {
     indicatorText = translate.weak;
diff --git a/core/modules/user/user.permissions.js b/core/modules/user/user.permissions.js
index 988820e..fb81830 100644
--- a/core/modules/user/user.permissions.js
+++ b/core/modules/user/user.permissions.js
@@ -1,5 +1,7 @@
 (function ($) {
 
+"use strict";
+
 /**
  * Shows checked and disabled checkboxes for inherited permissions.
  */
diff --git a/core/themes/bartik/color/preview.js b/core/themes/bartik/color/preview.js
index b40bcf7..423ea68 100644
--- a/core/themes/bartik/color/preview.js
+++ b/core/themes/bartik/color/preview.js
@@ -1,5 +1,7 @@
-
 (function ($) {
+
+  "use strict";
+
   Drupal.color = {
     logoChanged: false,
     callback: function(context, settings, form, farb, height, width) {