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Promisifying Callback-Based APIs in JavaScript

Does Node.js have built-in promise-based APIs for fs in JavaScript?

The answer

Yes. Use require('fs/promises') or require('fs').promises. These provide promise-based versions of fs methods (readFile, writeFile, etc.). No need to promisify manually.

More FAQs in Promisifying Callback-Based APIs in JavaScript

Return new Promise((resolve, reject) => { callbackApi(args, (err, result) => { if (err) reject(err); else resolve(result); }); }). The callback must follow the error-first convention.

A built-in utility that converts a callback-based function (error-first convention) to a promise-based one. Usage: const readFileP = promisify(fs.readFile). Then use with .then or async/await.

function delay(ms) { return new Promise(resolve => setTimeout(resolve, ms)); }. Then use await delay(1000) to pause. Node.js provides timers/promises with setTimeoutP for this.

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