Core: Fill in & warn against jQuery.proxy

Fixes jquerygh-460

Author: mgol

src/jquery/core.js

@@ -8,6 +8,8 @@ import {
 import "../disablePatches.js";
 
 var findProp,
+	arr = [],
+	slice = arr.slice,
 	class2type = {},
 	oldInit = jQuery.fn.init,
 	oldFind = jQuery.find,
@@ -176,4 +178,39 @@ if ( jQueryVersionSince( "3.3.0" ) ) {
 		}, "isWindow",
 		"jQuery.isWindow() is deprecated"
 	);
+
+	// Bind a function to a context, optionally partially applying any
+	// arguments.
+	// jQuery.proxy is deprecated to promote standards (specifically Function#bind)
+	// However, it is not slated for removal any time soon
+	migratePatchAndWarnFunc( jQuery, "proxy",
+		function( fn, context ) {
+			var tmp, args, proxy;
+
+			if ( typeof context === "string" ) {
+				tmp = fn[ context ];
+				context = fn;
+				fn = tmp;
+			}
+
+			// Quick check to determine if target is callable, in the spec
+			// this throws a TypeError, but we will just return undefined.
+			if ( typeof fn !== "function" ) {
+				return undefined;
+			}
+
+			// Simulated bind
+			args = slice.call( arguments, 2 );
+			proxy = function() {
+				return fn.apply( context || this, args.concat( slice.call( arguments ) ) );
+			};
+
+			// Set the guid of unique handler to the same of original handler, so it can be removed
+			proxy.guid = fn.guid = fn.guid || jQuery.guid++;
+
+			return proxy;
+		}, "proxy",
+		"jQuery.proxy() is deprecated"
+	);
+
 }

test/unit/jquery/core.js

@@ -449,3 +449,59 @@ TestManager.runIframeTest( "old pre-3.0 jQuery", "core-jquery2.html",
 
 		assert.ok( /jQuery 3/.test( log ), "logged: " + log );
 } );
+
+QUnit[ jQueryVersionSince( "3.3.0" ) ? "test" : "skip" ]( "jQuery.proxy", function( assert ) {
+	assert.expect( 10 );
+
+	var test2, test3, test4, fn, cb,
+		test = function() {
+			assert.equal( this, thisObject, "Make sure that scope is set properly." );
+		},
+		thisObject = { foo: "bar", method: test };
+
+	expectWarning( assert, "jQuery.proxy", 7, function() {
+
+		// Make sure normal works
+		test.call( thisObject );
+
+		// Basic scoping
+		jQuery.proxy( test, thisObject )();
+
+		// Another take on it
+		jQuery.proxy( thisObject, "method" )();
+
+		// Make sure it doesn't freak out
+		assert.equal( jQuery.proxy( null, thisObject ), undefined,
+			"Make sure no function was returned." );
+
+		// Partial application
+		test2 = function( a ) {
+			assert.equal( a, "pre-applied", "Ensure arguments can be pre-applied." );
+		};
+		jQuery.proxy( test2, null, "pre-applied" )();
+
+		// Partial application w/ normal arguments
+		test3 = function( a, b ) {
+			assert.equal( b, "normal", "Ensure arguments can be pre-applied and passed as usual." );
+		};
+		jQuery.proxy( test3, null, "pre-applied" )( "normal" );
+
+		// Test old syntax
+		test4 = {
+			"meth": function( a ) {
+				assert.equal( a, "boom", "Ensure old syntax works." );
+			}
+		};
+		jQuery.proxy( test4, "meth" )( "boom" );
+
+		// jQuery 1.9 improved currying with `this` object
+		fn = function() {
+			assert.equal( Array.prototype.join.call( arguments, "," ),
+				"arg1,arg2,arg3",
+				"args passed" );
+			assert.equal( this.foo, "bar", "this-object passed" );
+		};
+		cb = jQuery.proxy( fn, null, "arg1", "arg2" );
+		cb.call( thisObject, "arg3" );
+	} );
+} );