Implement ES6 Array.of()

src/harmony-array.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 'use strict';
 
 // This file relies on the fact that the following declaration has been made
 // in runtime.js:
 // var $Array = global.Array;
 
@@ skipping 105 matching lines @@
   if ((end - i) > 0 && ObjectIsFrozen(array)) {
     throw MakeTypeError("array_functions_on_frozen",
                         ["Array.prototype.fill"]);
   }
 
   for (; i < end; i++)
     array[i] = value;
   return array;
 }
 
+// ES6, draft 05-22-14, section 22.1.2.3
+function ArrayOf() {
+    var len = %_ArgumentsLength();
+    var C = this;
+    // TODO: Implement IsConstructor (ES6 section 7.2.5)
+    if (IS_SPEC_FUNCTION(C)) {
+        var A = new C(len);

[rossberg, 2014/07/21 16:07:07]

Please don't make use of var scoping like that. Preferred:

  var A = IS_SPEC_FUNCTION(C) ? new C(len) : []

Also, please use more descriptive names than A and C.

+    } else {
+        var A = [];
+    }
+    for (var k = 0; k < len; k++) {
+        %AddProperty(A, k, %_Arguments(k));

[rossberg, 2014/07/21 16:07:07]

Unfortunately, this runtime function has recently been removed (or rather,
specialised to AddNamedProperty). You probably have to implement your own
runtime function AddElement.

+    }
+    A.length = len;
+    return A;
+}
+
 // -------------------------------------------------------------------
 
 function HarmonyArrayExtendArrayPrototype() {
   %CheckIsBootstrapping();
 
+  // Set up non-enumerable functions on the Array object.
+  InstallFunctions($Array, DONT_ENUM, $Array(
+    "of", ArrayOf
+  ));
+
   // Set up the non-enumerable functions on the Array prototype object.
   InstallFunctions($Array.prototype, DONT_ENUM, $Array(
     "find", ArrayFind,
     "findIndex", ArrayFindIndex,
     "fill", ArrayFill
   ));
 }
 
 HarmonyArrayExtendArrayPrototype();