没有特别的幸运，那么就特别的努力！！！
异步处理：
方法一：在没有出现promise之前，处理异步——延时加载，setTimeout（）
function f1(callback){
setTimeout(()=>{
var res = 'f1'
console.log('我先执行从后台获取到了f1');
callback(res)
},1000)
}
function f2(value){
console.log(value);
}
f1(f2)
方法二：promise
// promise新建后会立即执行
console.log('hi');
const promise = new Promise(function(resolve,reject){
console.log('promise');
resolve()
})
promise.then(function(){
console.log('resolve');
})
console.log('hello');
es6 promise() 用法
Promise 是异步操作，用于解决回调函数和事件
模拟promise环境
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<script>
let status = 1;
//账号登录
let userLogin = (resolve,reject) => {
setTimeout(() => {
if(status == 1){
resolve({data:"登陆成功",msg:"xxxx",token:"afsafsd111"});
}else{
reject("失败");
}
},2000);
};
//登录成功 获取用户信息
let getUserInfo = (resolve,reject) => {
setTimeout(() => {
if(status == 1){
resolve({data:"获取用户信息成功",msg:"adsasfsd",token:"afsafsd222"});
}else{
reject("失败");
}
},1000);
}
//.then回调
new Promise(userLogin).then(res => {
console.log('用户登录成功')
console.log(res)
return new Promise(getUserInfo)
}).then(res => {
console.log("获取用户信息成功");
console.log(res)
})
</script>
</body>
</html>