从setTimeout获取返回值 [英] Get return value from setTimeout
本文介绍了从setTimeout获取返回值的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我只想从setTimeout获取返回值,但我得到的是该函数的整个文本格式?
I just want to get the return value from setTimeout but what i get is a whole text format of the function?
function x () {
setTimeout(y = function () {
return 'done';
}, 1000);
return y;
}
console.log(x());
推荐答案
您需要使用Promises。它们是在ES6中提供,但可以是polyfilled 非常轻松:
You need to use Promises for this. They are available in ES6 but can be polyfilled quite easily:
function x() {
var promise = new Promise(function(resolve, reject) {
window.setTimeout(function() {
resolve('done!');
});
});
return promise;
}
x().then(function(done) {
console.log(done); // --> 'done!'
});
async
/ 等待
在ES2017中如果在 async
函数内变得更好:
With async
/await
in ES2017 it becomes nicer if inside an async
function:
async function() {
const result = await x();
console.log(result); // --> 'done!';
}
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