Promise.resolve 与解决 [英] Promise.resolve vs resolve

问题描述

我有这个代码:

var promise1 = new Promise(function(resolve, reject) {
  setTimeout(() => {
         console.warn('Elo');
         resolve('First response');
      },
      1000);
})

promise1
.then((resp) => {
    console.warn('First then!');
    
});

它会在一秒钟后解析 promise 到 then 和 console.warning 'First then!'.

And It resolves promise after one second going to then and console.warning 'First then!'.

但是当我换行时:

resolve('First response');

为了

Promise.resolve('First response');

这行不通.知道为什么吗?

It won't work. Some idea why ?

也试过了

return Promise.resolve('First response');

但它也不起作用.我不知道为什么.

But it also doesn't work. I don't know why.

你能帮我理解吗?

推荐答案

new Promise 构造函数将特定函数传递到您的回调中，该函数成为您的 resolve 参数.该承诺(您使用 new Promise 在那里构建的承诺)只能通过调用特定的 resolve 函数来解决.

The new Promise constructor passes a specific function into your callback, which becomes your resolve parameter. That promise (the one you're constructing there with new Promise) can only be resolved by calling that specific resolve function.

Promise.resolve 只是创建一个新的预解析"承诺.它不会解析任何现有的承诺(也无法知道它应该解决哪个承诺).

Promise.resolve simply creates a new "pre-resolved" promise. It does not resolve any existing promise (nor would it have any way of knowing which promise it's supposed to resolve).

这篇关于Promise.resolve 与解决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！