三种状态

三种

1.pending 等待 冻结
2.fulfilled(resolved) 成功的状态 调用resolve函数,获取就是resolved状态
3.reject 调用reject(),获取reject的状态

        var  p = new Promise((resolve,reject)=>{
            reject(100)
        })
        console.log(p)
    </script>

promise状态的切换

        /* pending-->resolved */
        var p = new Promise((resolve,reject)=>[
            setTimeout(()=>{
                resolve(100)
            })
        ])
        console.log(p);
        setTimeout(()=>{
            console.log(p)
        })

promise-await

await只能得到Promise—resolved状态的结果,作用相当于then函数
Promise.reject(err).catch()捕获异常

        (async ()=>{
            var p = Promise.reject(100);
            var res = await p;
            console.log(res)

        })();