为什么我们在JS中需要Promise [英] Why do we need Promise in JS

问题描述

我刚刚在 MDN上都读到了关于Promise的内容.我可以理解语法，但是不确定为什么我们需要它.

I've just read about Promise on both MDN. I can understand the syntax but not sure about why we need it.

是否有只能通过Promise来完成的特定情况?还是只是编写更简洁的代码的一种方法?

Is there a specific case that can only be done by using Promise? Or is it just a way to write cleaner code?

推荐答案

承诺使我们能够编写更简洁的代码，但可以减少(或完全删除)回调地狱.

Promises give us the ability to write cleaner code but reducing (or entirely removing) call-back hell.

此外，回调是ES2017中一些新语法功能的中坚力量，例如 async functions (异步函数)，它允许更简洁的代码编写方式.

In addition, callbacks are the backbone of some new syntax features coming in ES2017, such as async functions, which allows an even cleaner way of writing code.

当您第一次学习语法时，承诺要做的第三件事并不是立即显而易见的-自动错误处理.承诺允许错误沿着链条传递并在一个公共位置进行处理，而不必进行手动错误处理.

The third thing that promises do is not immediately apparent when you first learn the syntax -- automatic error handling. Promises allow errors to be passed down the chain and handled in one common place without having to put in layers of manual error handling.

这篇关于为什么我们在JS中需要Promise的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！