foreach API说明：
https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach
说明：
forEach 遍历的范围在第一次调用 callback 前就会确定。调用forEach 后添加到数组中的项不会被 callback 访问到。如果已经存在的值被改变，则传递给 callback 的值是 forEach 遍历到他们那一刻的值。已删除的项不会被遍历到。如果已访问的元素在迭代时被删除了(例如使用 shift()) ，之后的元素将被跳过
示例：
<!DOCTYPE html><html lang="zh"> ???<head> ???????<meta charset="UTF-8" /> ???????<meta name="viewport" content="width=device-width, initial-scale=1.0" /> ???????<meta http-equiv="X-UA-Compatible" content="ie=edge" /> ???????<title>js foreach函数 注意事项</title> ???</head> ???<body> ???????<script src="https://cdn.bootcss.com/lodash.js/4.17.10/lodash.min.js"></script> ???????<script type="text/javascript"> ???????????var words = ["one", "two", "three", "four"]; ???????????words.forEach(function(word) { ???????????????console.log(word); ???????????????if(word === "two") { ???????????????????//会改变输出顺序 ???????????????????//words.shift(); ???????????????????//不会改变输出顺序 ???????????????????words.push(‘5‘) ???????????????????// 不能使用break ???????????????????//break ???????????????????//不能使用continue ???????????????????//continue ???????????????} ???????????}); ???????</script> ???</body></html>js foreach函数 注意事项(break、continue)
原文地址：https://www.cnblogs.com/mengfangui/p/9552525.html