5 files changed, 10 insertions, 0 deletions
diff --git a/src/event/ajax.js b/src/event/ajax.js
index 98e194bf0..500b36cdd 100644
--- a/src/event/ajax.js
+++ b/src/event/ajax.js
@@ -3,6 +3,8 @@ define( [
 	"../event"
 ], function( jQuery ) {
 
+"use strict";
+
 // Attach a bunch of functions for handling common AJAX events
 jQuery.each( [
 	"ajaxStart",
diff --git a/src/event/alias.js b/src/event/alias.js
index b1b8f701f..863c94ad2 100644
--- a/src/event/alias.js
+++ b/src/event/alias.js
@@ -5,6 +5,8 @@ define( [
 	"./trigger"
 ], function( jQuery ) {
 
+"use strict";
+
 jQuery.each( ( "blur focus focusin focusout resize scroll click dblclick " +
 	"mousedown mouseup mousemove mouseover mouseout mouseenter mouseleave " +
 	"change select submit keydown keypress keyup contextmenu" ).split( " " ),
diff --git a/src/event/focusin.js b/src/event/focusin.js
index c7af0df2c..7faef2981 100644
--- a/src/event/focusin.js
+++ b/src/event/focusin.js
@@ -7,6 +7,8 @@ define( [
 	"./trigger"
 ], function( jQuery, dataPriv, support ) {
 
+"use strict";
+
 // Support: Firefox <=44
 // Firefox doesn't have focus(in | out) events
 // Related ticket - https://bugzilla.mozilla.org/show_bug.cgi?id=687787
diff --git a/src/event/support.js b/src/event/support.js
index 1c4d416e5..e3db9ad83 100644
--- a/src/event/support.js
+++ b/src/event/support.js
@@ -2,6 +2,8 @@ define( [
 	"../var/support"
 ], function( support ) {
 
+"use strict";
+
 support.focusin = "onfocusin" in window;
 
 return support;
diff --git a/src/event/trigger.js b/src/event/trigger.js
index 8f5f77845..53acadbec 100644
--- a/src/event/trigger.js
+++ b/src/event/trigger.js
@@ -8,6 +8,8 @@ define( [
 	"../event"
 ], function( jQuery, document, dataPriv, acceptData, hasOwn ) {
 
+"use strict";
+
 var rfocusMorph = /^(?:focusinfocus|focusoutblur)$/;
 
 jQuery.extend( jQuery.event, {