How to return a promise when writestream finishes?

This question already has an answer here:

How do I convert an existing callback API to promises? 17 answers

---

你会想使用Promise构造函数：

function writeToFile(filePath: string, arr: string[]): Promise<boolean> {
  return new Promise((resolve, reject) => {
    const file = fs.createWriteStream(filePath);
    for (const row of arr) {
      file.write(row + "n");
    }
    file.end();
    file.on("finish", () => { resolve(true); }); // not sure why you want to pass a boolean
    file.on("error", reject); // don't forget this!
  });
}

---

You need to return the Promise before the operation was done.
Something like:

function writeToFile(filePath: string, arr: string[]): Promise<boolean> {
    return new Promise((resolve, reject) => {
        const file = fs.createWriteStream(filePath);
        arr.forEach(function(row) {
            file.write(row + "n");
        });
        file.end();
        file.on("finish", () => { resolve(true) });
    });
}

链接地址: http://www.djcxy.com/p/55514.html

上一篇: 如何从回调函数创建返回承诺的函数

下一篇: writestream完成时如何返回承诺？