Variables Rules in javascript

Variable names must start with a letter, $, or _. They cannot start with a number or be reserved keywords (like if, for, class). Always declare variables (with let/const) before using them, avoid reusing the same name in the same scope, and use const by default unless you truly need to reassign.

Example

// ✅ valid
const userName = "punam";
let $count = 0;
let _isReady = true;

// ❌ invalid
// let 1user = "x";    // starts with a number
// let class = "A";    // reserved keyword

// Style rules
const MAX_RETRIES = 3; // UPPER_SNAKE_CASE for constants

Good variable naming rules improve readability and avoid subtle bugs caused by accidental shadowing or use of reserved words.

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