var arr = new Array(1000);console.time('forEach');arr.forEach(data => {});console.timeEnd('forEach');console.time('for');for (var i = 0; i < arr.length; ++i) {};console.timeEnd('for');console.time('for in');for (var i in arr) {};console.timeEnd('for in');console.time('for of');for (var i of arr) {};console.timeEnd('for of');

　　打印结果为

结论性能为forEach > for in > for > for of