Why Cursor uses deprecated APIs

1---
2description: Node.js API version rules
3globs: "src/**/*.ts,src/**/*.js"
4alwaysApply: true
5---
6
7## Node.js Version: 22 (LTS)
8
9## Deprecated → Modern Replacements
10| Deprecated | Use Instead |
11|-----------|------------|
12| url.parse() | new URL() |
13| querystring.parse() | URLSearchParams |
14| fs.exists() | fs.access() or fs.stat() |
15| fs.readFile(cb) | fs.promises.readFile() |
16| Buffer(string) | Buffer.from(string) |
17| util.puts() | console.log() |
18| domain module | AsyncLocalStorage |
19| util.isArray() | Array.isArray() |
20| require() in ESM | import |
21| crypto.createCipher() | crypto.createCipheriv() |
22
23## Rules
24- ALWAYS use fs.promises (import fs from 'node:fs/promises')
25- ALWAYS use node: protocol prefix (node:fs, node:path, node:crypto)
26- NEVER use callback-based fs methods
27- Use native fetch() instead of http.request() for HTTP calls
28- Use structuredClone() instead of JSON.parse(JSON.stringify())
29- Use AbortController instead of manual timeout handling

1// In Cursor Settings → Features → Docs:
2// 1. Click 'Add new doc'
3// 2. Enter URL: https://nodejs.org/api/
4// 3. Name it: 'Node.js 22 API'
5// 4. Wait for indexing to complete
6//
7// Now use in prompts:
8// @docs:Node.js 22 API Generate a file reader using the
9// current recommended fs API.

1// Cursor Chat prompt (Cmd+L, Ask mode):
2// @codebase Find all uses of deprecated Node.js APIs in src/:
3// 1. url.parse() → should be new URL()
4// 2. querystring.parse() → should be URLSearchParams
5// 3. Callback-based fs (fs.readFile with callback)
6//    → should be fs.promises.readFile()
7// 4. Buffer() constructor → should be Buffer.from()
8// 5. require() in .ts files → should be import
9// 6. fs without node: prefix → should be node:fs
10// List each finding with file, line, and the modern replacement.

1// DEPRECATED:
2const parsed = url.parse(req.url, true);
3const name = parsed.query.name;
4
5// Select and press Cmd+K:
6// 'Replace url.parse with new URL(). Use Node.js 22 API.'
7
8// MODERN:
9const parsed = new URL(req.url, `http://${req.headers.host}`);
10const name = parsed.searchParams.get('name');

1// Terminal: Run with deprecation warnings
2NODE_OPTIONS='--throw-deprecation' npm test
3
4// This makes Node.js throw an error (not just warn) when
5// deprecated APIs are called, ensuring all are caught.
6//
7// Common deprecation warnings:
8// DEP0005: Buffer() constructor
9// DEP0025: require('sys')
10// DEP0079: url.resolve()
11// DEP0106: crypto.createDecipher()