SOURCE

function Async1(){
    var p =new Promise(function(resolve,reject){
        setTimeout(function(){
            console.log('异步任务1执行完成');
            resolve('1中的成功数据')
        },1000)
    });
    return p
}


function Async2(){
    var p =new Promise(function(resolve,reject){
        setTimeout(function(){
            console.log('异步任务2执行成功');
            resolve('2中的成功数据')
        },2000)
    })
    return p;
}

function Async3(){
    var p = new Promise(function(resolve,reject){
        setTimeout(function(){
            console.log('异步任务3执行成功');
            resolve('3中的成功数据')
        },3000)
    });
    return p;
}

Async1()
.then(function(data){
    console.log('Async1中的data',data)
    return Async2()
})
.then(function(data){
    console.log('Async2中的data',data)
    return Async3()
})
.then(function(data){
    console.log('最后拿到Async3中的数据')
})


function getNumber(){
    var p = new Promise(function(resolve,reject){
        setTimeout(function(){
            var num = Math.ceil(Math.random()*10);
            if(num<=5){
                resolve(num)
            }else{
                reject('数字大于5了')
            }
        },2000)
    });
    return p
}
getNumber()
.then(
    function(data){
        console.log('resolved');
        console.log(data)
    },
    function(reason,data){
        console.log('rejected');
        console.log(reason)
    }
)