// 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. // Arrow functions are like functions, except they throw when using the // "new" operator on them. assertEquals("function", typeof (() => {})); assertEquals(Function.prototype, Object.getPrototypeOf(() => {})); assertThrows(function() { new (() => {}); }, TypeError); assertFalse("prototype" in (() => {})); // Check the different syntax variations assertEquals(1, (() => 1)()); assertEquals(2, (a => a + 1)(1)); assertEquals(3, (() => { return 3; })()); assertEquals(4, (a => { return a + 3; })(1)); assertEquals(5, ((a, b) => a + b)(1, 4)); assertEquals(6, ((a, b) => { return a + b; })(1, 5)); // The following are tests from: // http://wiki.ecmascript.org/doku.php?id=harmony:arrow_function_syntax // Empty arrow function returns undefined var empty = () => {}; assertEquals(undefined, empty()); // Single parameter case needs no parentheses around parameter list var identity = x => x; assertEquals(empty, identity(empty)); // No need for parentheses even for lower-precedence expression body var square = x => x * x; assertEquals(9, square(3)); // Parenthesize the body to return an object literal expression var key_maker = val => ({key: val}); assertEquals(empty, key_maker(empty).key); // Statement body needs braces, must use 'return' explicitly if not void var evens = [0, 2, 4, 6, 8]; assertEquals([1, 3, 5, 7, 9], evens.map(v => v + 1)); var fives = []; [1, 2, 3, 4, 5, 6, 7, 8, 9, 10].forEach(v => { if (v % 5 === 0) fives.push(v); }); assertEquals([5, 10], fives); (function testRestrictedFunctionPropertiesStrict() { var arrowFn = () => { "use strict"; }; assertFalse(arrowFn.hasOwnProperty("arguments")); assertThrows(function() { return arrowFn.arguments; }, TypeError); assertThrows(function() { arrowFn.arguments = {}; }, TypeError); assertFalse(arrowFn.hasOwnProperty("caller")); assertThrows(function() { return arrowFn.caller; }, TypeError); assertThrows(function() { arrowFn.caller = {}; }, TypeError); })(); (function testRestrictedFunctionPropertiesSloppy() { var arrowFn = () => {}; assertFalse(arrowFn.hasOwnProperty("arguments")); assertThrows(function() { return arrowFn.arguments; }, TypeError); assertThrows(function() { arrowFn.arguments = {}; }, TypeError); assertFalse(arrowFn.hasOwnProperty("caller")); assertThrows(function() { return arrowFn.caller; }, TypeError); assertThrows(function() { arrowFn.caller = {}; }, TypeError); })(); // v8:4474 (function testConciseBodyReturnsRegexp() { var arrow1 = () => /foo/ var arrow2 = () => /foo/; var arrow3 = () => /foo/i var arrow4 = () => /foo/i; assertEquals(arrow1.toString(), "() => /foo/"); assertEquals(arrow2.toString(), "() => /foo/"); assertEquals(arrow3.toString(), "() => /foo/i"); assertEquals(arrow4.toString(), "() => /foo/i"); });