// 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. // Note: concat does not currently support species so there is no difference // between [].concat(foo) and Array.prototype.concat.apply(foo). var log = []; var logger = {}; var handler = new Proxy({}, logger); logger.get = function(t, trap, r) { return function(...args) { log.push([trap, ...args]); return Reflect[trap](...args); } }; var target = {0: "a", 1: "b"}; var obj = new Proxy(target, handler); log.length = 0; assertEquals([obj], [].concat(obj)); assertEquals(1, log.length); for (var i in log) assertSame(target, log[i][1]); assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]); log.length = 0; assertEquals([obj], Array.prototype.concat.apply(obj)); assertEquals(1, log.length); for (var i in log) assertSame(target, log[i][1]); assertEquals(["get", target, Symbol.isConcatSpreadable, obj], log[0]);