proise:
1.Promise是异步编程的一种解决方案,它有三种状态,分别是pending-进行中、resolved-已完成、rejected-已失败
2.创建实例
//method1
let promise=new Promise((resolve,reject)=>{
if(success){
resolve();
}else{
reject();
}
})
//method2
function promise(){
return new Promise(function(resolve,reject){
if(success){
resolve();
}else{
reject();
}
})
}
3.Promise.prototype.then() VS Promise.prototype.catch()
.then()方法使Promise原型链上的方法,它包含两个参数方法,分别是已成功resolved的回调和已失败rejected的回调
promise.then(
() => { console.log('this is success callback') },
() => { console.log('this is fail callback') }
)
应该用