如何使用异步等待包装回叫? [英] How do i wrap a callback with async await?

问题描述

我的函数解析了一个承诺，该承诺将在http服务器启动时立即解决.这是我的代码:

My function resolves a promise that resolves as soon as the http server starts. This is my code:

function start() {
    return new Promise((resolve, reject) {
        this.server = Http.createServer(app);
        this.server.listen(port, () => {
            resolve();
        });
    })
}

如何将启动功能转换为异步/等待?

How do i convert the start function to async/await?

推荐答案

在函数声明之前包含async，在await中包含Promise构造函数.尽管要注意，实际上您将在现有模式中添加代码.尽管Question上的代码已经使用了Promise构造函数，但await会将值转换为Promise.

Include async before the function declaration and await the Promise constructor. Though note, you would essentially be adding code to the existing pattern. await converts a value to a Promise, though the code at Question already uses Promise constructor.

async function start() {
    let promise = await new Promise((resolve, reject) => {
        this.server = Http.createServer(app);
        this.server.listen(port, () => {
            resolve();
        });
    })
    .catch(err => {throw err});

    return promise
}

start()
.then(data => console.log(data))
.catch(err => console.error(err));

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