Iterator

[yongzeng]

for循环 最原始

for (var index = 0; index < myArray.length; index++) { }

forEach 无法跳出循环 ES5

myArray.forEach(item=>{})

for in 对象的循环

for (let i in arr) {} i是键名，键名会转化成字符串。会乱序

for of 数组的循环，替代forEach ES6

for (let i of arr) {} i是键值 键名需要是数字(Uncaught TypeError: object is not iterable)