Question

我的.then()链printer.done()如何显示我的信息？

printer.done()应该显示一个消息模板。

   .then(() => {
    const whileHeapList = () => {
        setTimeout(() => {
            console.log(new Date());
            console.log(1);
            setTimeout(() => {
                console.log(2);
                console.log(new Date());
            }, 5000)
        }, 5000);
    };
    whileHeapList();
    }).then(() => {
        printer.done()
    });

我想让我的代码做的是记录1，等待5秒记录2，然后打印出printer.done()模板消息

现在这是输出：

** TEMPLATE **

2017-01-30T04:19:54.111Z
1
2
2017-01-30T04:19:59.118Z

Answer 1

如果您希望第二个.then等待第二个setTimeout完成，则需要返回第二个.then解析后的第一个setTimeout的承诺}火

.then(function () {
    var whileHeapList = function whileHeapList() {
        return new Promise(function(resolve) { // added
            setTimeout(function () {
                console.log(new Date());
                console.log(1);
                setTimeout(function () {
                    console.log(2);
                    console.log(new Date());
                    resolve(); // added
                }, 5000);
            }, 5000);
        }); // added
    };
    return whileHeapList(); // added a return
}).then(function () {
    printer.done();
});

或者，使用你评论中的尝试代码

.then(function () {
    var whileHeapList = function whileHeapList(resolve) {
        setTimeout(function () {
            console.log(new Date());
            console.log(1);
            setTimeout(function () {
                console.log(2);
                console.log(new Date());
                resolve(); // added
            }, 5000);
        }, 5000);
    };
    return new Promise(whileHeapList);
}).then(function () {
    printer.done();
});

Answer 2

我做了一个睡眠功能和链接

const sleep = (ms) => new Promise(resolve => setTimeout(resolve, ms));

...    

.then(() => sleep(5000))
.then(() => console.log(1, new Date()))
.then(() => sleep(5000))
.then(() => console.log(2, new Date()))
.then(() => printer.done())

.then（）用promises订购

2 个答案: