javascript

name	javascript
description	JavaScript and TypeScript language patterns — const/let, async/await, ESM imports, and typed unknowns. Use when writing or reviewing JS/TS in frontend or backend. Don't use for React component patterns (use react), general file-size or nesting standards (use code-standards), or test structure (use tests).

JavaScript and TypeScript

Apply these language patterns to frontend and backend JS/TS. For file size, nesting, and related shape rules, invoke code-standards in full. For React components and hooks, invoke react in full.

Reference — language rules

const by default

Declare with const whenever the binding is not reassigned. Use let only when reassignment is required. Mutating an object's contents does not require let — the binding stays const.

async/await

Drive async flow with async/await and explicit try/catch when errors must be handled. For independent work, combine with Promise.all:

const [user, settings] = await Promise.all([
  loadUser(userId),
  loadSettings(userId),
]);

ESM in Node

In backend Node code, use import/export. Use import type for type-only imports.

import express  ;
  { ,  }  ;
 { getHealth }  ;

  app = ();