Comments (3)
EventEmitter
- 事件触发 事件监听
from blog.
Promise执行顺序
let promise = new Promise(function(resolve, reject) {
console.log('Promise');
resolve();
});
promise.then(function() {
console.log('resolved.');
});
console.log('Hi!');
// Promise
// Hi!
// resolved
Promise
新建后立即执行
,所以首先输出的是Promise
。
然后,then
方法指定的回调函数,将在当前脚本所有同步任务执行完才会执行,所以resolved最后输出
from blog.
await在等啥
var t = async function() {
return 1
}
var s = async function () {
console.log(t()) // 返回结果: Promise {<resolved>: 1}
console.log(await t()) // 返回结果:1
}
s()
- 如果它等到的是一个 Promise 对象,await 就忙起来了,它会阻塞后面的代码,等着 Promise 对象 resolve,然后得到 resolve 的值,作为 await 表达式的运算结果
from blog.
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