短路Array.forEach就像调用break [英] Short circuit Array.forEach like calling break

问题描述

[1,2,3].forEach(function(el) {
    if(el === 1) break;
});

如何使用新的 forEach JavaScript中的方法？我试过 return; ，返回false; 和 break 。 中断崩溃和返回除了继续迭代之外什么都不做。

How can I do this using the new forEach method in JavaScript? I've tried return;, return false; and break. break crashes and return does nothing but continue iteration.

推荐答案

forEach 中没有内置的中断的能力。要中断执行，你必须抛出某种异常。例如。

There's no built-in ability to break in forEach. To interrupt execution you would have to throw an exception of some sort. eg.

var BreakException = {};

try {
  [1, 2, 3].forEach(function(el) {
    console.log(el);
    if (el === 2) throw BreakException;
  });
} catch (e) {
  if (e !== BreakException) throw e;
}

JavaScript异常并不是非常漂亮。如果你真的需要 break ，那么传统的 for 循环可能更合适。

JavaScript exceptions aren't terribly pretty. A traditional for loop might be more appropriate if you really need to break inside it.

相反，请使用 Array＃some ：

Instead, use Array#some:

[1, 2, 3].some(function(el) {
  console.log(el);
  return el === 2;
});

这是因为 some 返回 true 只要以数组顺序执行的任何回调，返回 true ，短路其余的执行。

This works because some returns true as soon as any of the callbacks, executed in array order, return true, short-circuiting the execution of the rest.

一些，其反向 每个 （将停在返回false ）和 forEach 是所有ECMAScript第五版方法，需要在缺少它们的浏览器上添加到 Array.prototype 。

some, its inverse every (which will stop on a return false), and forEach are all ECMAScript Fifth Edition methods which will need to be added to the Array.prototype on browsers where they're missing.

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