then之后的返回值的状态 resolved,如果遇到错误,状态会变成reject

        var p = Promise.resolve(100).then((res)=>{
            console.log(res)
            throw "err"
        })
        console.log(p)

then-throw

then之后的返回值的状态 resolved,如果遇到错误,状态会变成reject
Tips: then只能触发promise—>resolved的状态

        var p = Promise.resolve(100).then((res) => {
            console.log(res)
            throw "err"
        })
        p.then(()=>{
            console.log(200)
        })

then-thow

then之后的Promise返回值的状态 resolved,如果遇到错误,状态会变成reject
Tips: then只能触发promise—>resolved的状态

        var p = Promise.resolve(100).then((res) => {
            console.log(res)
            throw "err"
        })
        p.then(()=>{
            console.log(200)
        }).catch(err=>{
            console.log(err)
        })

catch-throw

        var p = Promise.resolve(100).then((res) => {
            console.log(res)
            throw "err"
        })
        p.then(() => {
            console.log(200)
        }).catch(err => {
            console.log(err)
        }).then(()=>{
            console.log(300)
        })

catch的返回值 Promise的状态,正常情况下是resolved,如果有错误,那么状态是rejected

        var p = Promise.reject(100).catch(res=>{
            console.log(res)
            throw "err"
        })
        console.log(p)

async-try

在async-await中可以使用try-catch语句去捕获异常
Promise.reject(“err”).catch()

        (async ()=>{
            var p = Promise.reject("err");
            try{
                let res = await p;
                console.log(res)
            }catch(err){
                console.log(err)
            }
        })();