Question

我正在尝试使用“ reduce”设置顺序解析，然后继续进行其他工作，但是它似乎并不在等待，而是继续进行。我如何等待阵列中的每个诺言完成？

function Work(data){
    return new Promise((resolve)=>{resolve()});
}
function DoWork(data){
    return new Promise((resolve, reject)=>{
        setTimeout(() => {
            Work(data)
                .then(() => {
                    console.log("Doing work on '"+data+"'");
                    resolve();
                })
                .catch(err => {
                    console.log("Failed to do work on '"+data+"'");
                    reject(err);
                });
        }, 1000);
    });
}
var AllMyWork= ["a","b","c"];
AllMyWork.reduce((p, data) => p.then(DoWork(data)), Promise.resolve())
.then(result => {
    console.log("All work is finished");
})
.catch(err => {
    console.log("MyArray reduce has failed");
});

这就是我得到的回报：

All work is finished
Doing work on 'a'
Doing work on 'b'
Doing work on 'c'

我想做的就是等所有工作都完成后再写msg“所有工作都完成了。”

Answer 1

p.then(DoWork(data))

这会立即调用DoWork。您要将函数传递给.then：

p.then(() => DoWork(data))

否则减少就可以了。示例：

delay = ms => new Promise(resolve => setTimeout(resolve, ms));

DoWork = work => delay(1000).then(() => console.log("did work", work));

AllMyWork = ["a","b","c"];
AllMyWork.reduce((p, data) => p.then(() => DoWork(data)), Promise.resolve())
.then(result => {
    console.log("All work is finished");
});

等待直到顺序承诺得到解决，然后再继续在节点

1 个答案: