node.js - 不回调 Node js 写入文件

Question

如何编写没有回调的 writeFile() 函数？

这不起作用:

fs.writeFile("/logs/file.log", 'Message')

fs.writeFile("/logs/file.log", 'Message',null)

两者都抛出:

TypeError [ERR_INVALID_CALLBACK]: Callback must be a function

我需要实现一个非阻塞解决方案。

Answer 1

// create a noop - as in "no operation"
const noop = () => {};

// and pass that in
fs.writeFile("filename.txt", "content", noop);

如果您对必须传递回调感到烦恼，请创建另一个函数:

const writeFile = (filename, content) => {fs.writeFile(filename, content, () => {}));

// and use it like this
writeFile("filename.txt", "content");

更好的是，如果您使用的是 NodeJS > v10.0，则使用 fs.promises.writeFile API:

import fs from "fs";

// this returns a Promise
fs.promises.writeFile("filename.txt", "content");

// which you can await in an async function
async main() {
    try {
        await fs.promises.writeFile("filename.txt", "content");
    }
    catch (e) {
        console.error(e);
    }
}

// or .then and .catch on it.
fs.promises.writeFile("filename.txt", "content")
    .then(() => { /* do something after */ })
    .catch(e => console.error(e));

如果在 Node < v10.0 上，您可以使用 promisify 实用程序:

import { promisify } from "util";
import fs from "fs";

const writeFile = promisify(fs.writeFile);

// this returns a Promise that you can await or .then
await writeFile("filename.txt", "content");