Add Array.prototype.includes

src/harmony-array-includes.js

+// Copyright 2014 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 $Array = global.Array;
+
+// -------------------------------------------------------------------
+
+// Proposed for ES7
+// https://github.com/tc39/Array.prototype.includes
+// 6e3b78c927aeda20b9d40e81303f9d44596cd904
+function ArrayIncludes(searchElement, fromIndex) {
+  var array = ToObject(this);
+  var len = ToLength(array.length);
+
+  if (len === 0) {
+    return false;
+  }
+
+  var n = ToInteger(fromIndex);
+
+  var k;
+  if (n >= 0) {
+    k = n;
+  } else {
+    k = len + n;
+    if (k < 0) {
+      k = 0;
+    }
+  }
+
+  while (k < len) {
+    var elementK = array[k];
+    if (SameValueZero(searchElement, elementK)) {
+      return true;
+    }
+
+    ++k;
+  }
+
+  return false;
+}
+
+// -------------------------------------------------------------------
+
+function HarmonyArrayIncludesExtendArrayPrototype() {
+  %CheckIsBootstrapping();
+
+  %FunctionSetLength(ArrayIncludes, 1);
+
+  // Set up the non-enumerable functions on the Array prototype object.
+  InstallFunctions($Array.prototype, DONT_ENUM, $Array(
+    "includes", ArrayIncludes
+  ));
+}
+
+HarmonyArrayIncludesExtendArrayPrototype();