Sync plugins from current page

Signed-off-by: Adrian Nöthlich <git@promasu.tech>

wp-content/plugins/advanced-custom-fields/assets/build/js/_acf-unload.js

@@ -0,0 +1,62 @@
+(function($, undefined){
+	
+	acf.unload = new acf.Model({
+		
+		wait: 'load',
+		active: true,
+		changed: false,
+		
+		actions: {
+			'validation_failure':	'startListening',
+			'validation_success':	'stopListening'
+		},
+		
+		events: {
+			'change form .acf-field':	'startListening',
+			'submit form':				'stopListening'
+		},
+		
+		enable: function(){
+			this.active = true;
+		},
+		
+		disable: function(){
+			this.active = false;
+		},
+		
+		reset: function(){
+			this.stopListening();
+		},
+		
+		startListening: function(){
+			
+			// bail ealry if already changed, not active
+			if( this.changed || !this.active ) {
+				return;
+			}
+			
+			// update 
+			this.changed = true;
+			
+			// add event
+			$(window).on('beforeunload', this.onUnload);
+			
+		},
+		
+		stopListening: function(){
+			
+			// update 
+			this.changed = false;
+			
+			// remove event
+			$(window).off('beforeunload', this.onUnload);
+			
+		},
+		
+		onUnload: function(){
+			return acf.__('The changes you made will be lost if you navigate away from this page');
+		}
+		 
+	});
+	
+})(jQuery);