promise小练习

    /*
    var p = new Promise(function(resolve, reject) {
        console.log("create a promise");
        resolve("success");
    });
    console.log("after new Promise");
    p.then(function(value) {
        console.log(value);
    });
    
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    Promise.resolve(11)
    .then((res) => {
        console.log(res)
        return 2
    })
    .catch((err) => {
        return 3
    })
    .then((res) => {
        console.log("res")
    })
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    function taskA() {
        console.log("Task A");
    }
    
    function taskB() {
        console.log("Task B");
    }
    
    function onRejected(error) {
        console.log("Catch Error: A or B", error);
    }
    
    var promise = Promise.resolve();
    promise
        .then(taskA)
        .then(taskB)
        .catch(onRejected) // 捕获前面then方法中的异常
        
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    let p = new Promise(function (resolve, reject) {
        resolve("蚂蚁部落");
    })
    p.then(function (val) {
        console.log(val) 
    })
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    let p = new Promise(function(resolve, reject) {
        console.log("蚂蚁部落一");
        resolve("蚂蚁部落二");
    })
    p.then(function(val) {
        console.log(val)
    })
    console.log("蚂蚁部落三");
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    setTimeout(function(){
      console.log("index");
    },0); 
    console.log("蚂蚁部落");
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    let p = new Promise(function(resolve, reject) {
        resolve("蚂蚁部落");
    });
    p.then(function(value) {
        console.log(value);
        return value + "前端";
    }).then(function(value) {
        console.log(value);
    });
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    const promises = [
        Promise.resolve('a'),
        Promise.resolve('b'),
        Promise.resolve('c'),
    ];
    Promise.all(promises)
        .then((arr) => 
            console.log(arr)
    );
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    function timesTwoAsync(x) {
      return new Promise(resolve => resolve(x * 3));
    }
    const arr = [1, 2, 3];
    const promiseArr = arr.map(timesTwoAsync);
    Promise.all(promiseArr)
        .then(result => {
            console.log(result)
        }
    );
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    const urls = [
      'http://example.com/first.txt',
      'http://example.com/second.txt',
    ];
    const promises = urls.map(
        url => downloadText(url)
    );
    
    Promise.all(promises)
    .then(result => {
            console.log(result)
        }
    );
    //xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
    function putDookieInAnyArray(arr) {
        return [...arr, 'dookie'];
    }
    const result = putDookieInAnyArray(['I', 'really', "don't", 'like']); 
    console.log(result)
    // ["I", "really", "don't", "like", "dookie"]
    const person = {
        name: 'Todd',
        age: 29,
    };
    const copyOfTodd = { ...person };
    console.log(copyOfTodd)
    */