一个很low的问题，forEach怎么跳出循环？

• 2019 年 12 月 4 日
• 筆記

方法一： try catch

const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];  const _ = require('lodash');    let outArr = [];  try {      arr.forEach(obj => {          console.log(obj);          if (obj < 3) {              outArr.push(obj);          } else {              throw new Error('brack');          }      });  } catch (err) {  }

方法二：污染forEach

代码偷自https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Array/every

const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];    Array.prototype.forEach = function(fun /*, thisArg */)    {      'use strict';        if (this === void 0 || this === null)        throw new TypeError();        var t = Object(this);      var len = t.length >>> 0;      if (typeof fun !== 'function')          throw new TypeError();        var thisArg = arguments.length >= 2 ? arguments[1] : void 0;      for (var i = 0; i < len; i++)      {        if (i in t && fun.call(thisArg, t[i], i, t) === false)          return false;      }        return true;    };    let outArr = [];    arr.forEach(obj => {      console.log(obj);      if (obj < 3) {          outArr.push(obj);      } else {          return false;      }  });

方法三：用替代品

1：用lodash的_.forEach代替

const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];  const _ = require('lodash');  let outArr = [];  _.forEach(arr, (index, obj) => {      console.log(obj);      if (obj < 3) {          outArr.push(obj);      } else {          return false;      }  });

2：用every代替

const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];  let outArr = [];  arr.every((obj) => {      console.log(obj);      if (obj < 3) {          outArr.push(obj);      } else {          return false;      }        return true;  });

3：用some代替

const arr = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];  let outArr = [];  arr.some((obj) => {      console.log(obj);      if (obj < 3) {          outArr.push(obj);      } else {          return true;      }  });

4：for代替

5：while代替

6：do while代替