// 執(zhí)行FN1返回一個(gè)promise實(shí)例，實(shí)例中管理了一個(gè)異步編程的代碼，當(dāng)定時(shí)器到時(shí)間后，才會(huì)把實(shí)例的狀態(tài)改為成功
const fn1 = () => {
    return new Promise(resolve => {
        setTimeout(() => {
            resolve(1);
        }, 1000);
    });
};
const fn2 = () => {
    return new Promise(resolve => {
        setTimeout(() => {
            resolve(2);
        }, 2000);
    });
};
const fn3 = () => {
    return new Promise(resolve => {
        setTimeout(() => {
            resolve(3);
        }, 3000);
    });
}; 


// 異步的“并行”：同時(shí)處理，相互之間沒啥依賴
fn1().then(result => {
    console.log(result);
});
fn2().then(result => {
    console.log(result);
});
fn3().then(result => {
    console.log(result);
}); 

let p = Promise.all([Promise.resolve(100), fn1(), 200, fn3(), fn2()]); //瀏覽器默認(rèn)會(huì)把200 變?yōu)橐粋€(gè)成功的promsie實(shí)例
p.then(results => {
    console.log(`成功：${results}`); // 成功：100,1,200,3,2 順序和最開始是一致的，不會(huì)考慮誰(shuí)先成功
}).catch(reason => {
    console.log(`失?。?{reason}`);
}); 

//new Error('xxx')不是promise實(shí)例=》Promise.resolve(new Error('xxx')) 值是Error對(duì)象
let p = Promise.all([Promise.resolve(100), fn1(), new Error('xxx'), Promise.reject(200), fn3(), fn2()]);
p.then(results => {
    console.log(`成功：${results}`);
}).catch(reason => {
    console.log(`失?。?{reason}`); //失?。?00 遇到錯(cuò)誤直接返回
}); 

//=>等三個(gè)異步都成功做什么事情 所用時(shí)間3s
Promise.all([fn1(), fn2(), fn3()]).then(results => {
    console.log(`三個(gè)異步都成功了，分別的結(jié)果：${results}`);
}); 

fn1().then(result => {
    console.log(`第一個(gè)成功:${result}`);
    return fn2();
}).then(result => {
    console.log(`第二個(gè)成功:${result}`);
    return fn3();
}).then(result => {
    console.log(`第三個(gè)成功:${result}`);
}).catch(reason => {
    console.log(`只要其中一個(gè)失敗，直接順延到這里，其余剩下的請(qǐng)求就不發(fā)送了!`);
});

(async function () {
    let result = await fn1();
    console.log(`第一個(gè)成功:${result}`);

    result = await fn2();
    console.log(`第二個(gè)成功:${result}`);

    result = await fn3();
    console.log(`第三個(gè)成功:${result}`);
})();

async function fn() {
    return 10;
}
fn().then(result => {
    console.log(result);//輸出10
}); 

async function fn() {
    return async function () {
        return 10;
    };
}
fn().then(result => {
    // result:async function () {...}  函數(shù)
    return result();
}).then(result => {
    console.log(result); //10
}); 

const fn1 = () => {
    return new Promise(resolve => {
        setTimeout(() => {
            resolve(1);
        }, 1000);
    });
};
(async function () {
    let result = await fn1();
    console.log(result); 
  //下面代碼可以執(zhí)行，說明await后面的promise實(shí)例，它的狀態(tài)已經(jīng)是成功了，await的返回值就是當(dāng)前promise實(shí)例的值
    console.log('OK');
})(); 


//=======================如果await后面的promise實(shí)例狀態(tài)是失敗的
const fn1 = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            reject(0);
        }, 1000);
    });
};
(async function () {
    let result = await fn1(); //如果await后面的promise實(shí)例狀態(tài)是失敗的，則下面代碼永遠(yuǎn)都不會(huì)執(zhí)行了
    console.log(result);
    console.log('OK');//如果是失敗的則這句話不會(huì)執(zhí)行
})();

//===================================================
(async function () {
    let a = await 10; //->Promise.resolve(10)
    console.log(a); //10
    let b = await Promise.resolve(20);
    console.log(b); //20
    try {
        let c = await Promise.reject(30); //Uncaught (in promise) 30
        console.log(c);
    } catch (err) {
        console.log(err); //30
    }
    console.log('OK'); //'OK'
})(); 

(async function () {
    let b = await Promise.resolve(20);
    console.log(b);
})()

console.log(1);
setTimeout(() => { console.log(2); });//宏1
console.log(3);
let p1 = new Promise(resolve => {//new Promise 立即會(huì)把executor函數(shù)執(zhí)行 是同步
    console.log(4);
    resolve('A'); //執(zhí)行resolve P1的狀態(tài)是成功=》已知
    console.log(5);
});
console.log(6);
p1.then(result => {//.then是異步 已知狀態(tài) 放進(jìn)WebAPI中監(jiān)聽 但是因?yàn)槭且阎獱顟B(tài) 方法肯定執(zhí)行 則從WebAPI監(jiān)聽隊(duì)列挪到EventQueue中等待
    console.log(result); //微1
});
console.log(7);
let p2 = new Promise(resolve => { //立即執(zhí)行executor函數(shù) setTimeout是異步則會(huì)放進(jìn)WebAPI監(jiān)聽 宏2
    setTimeout(() => {
        resolve('B');
        console.log(10); //執(zhí)行宏2=>@1 更改了p2的狀態(tài) @2之前存儲(chǔ)的.then方法執(zhí)行
    });
});
console.log(8);
p2.then(result => {//p2的狀態(tài)是未知?jiǎng)t會(huì)先存起來
    console.log(result);
});
console.log(9);

let body = document.body;
body.addEventListener('click', function () {
    Promise.resolve().then(() => {
        console.log(1);
    });
    console.log(2);
});
body.addEventListener('click', function () {
    Promise.resolve().then(() => {
        console.log(3);
    });
    console.log(4);
}); 

 async function async1() {
    console.log('async1 start');
    await async2();
    console.log('async1 end');
}
async function async2() {
    console.log('async2');
}
console.log('script start');
setTimeout(function () {
    console.log('setTimeout');
}, 0)
async1();
new Promise(function (resolve) {
    console.log('promise1');
    resolve();
}).then(function () {
    console.log('promise2');
});
console.log('script end');