← Back to Roadmap

Reserved Keywords

Easy

In plain terms

Reserved keywords like if, for, function, return cannot be used as variable names. Avoid naming variables after built-in objects (e.g., name, length) to prevent shadowing.

What you need to know

  • •if, else, for, while, function, return, etc.
  • •Cannot use as identifiers
  • •Contextual keywords (await, yield)

Try it yourself

Copy the code below and run it in your browser console or a code editor:

// Invalid - reserved
// let if = 1;
// const for = 2;

// Valid
let myIf = 1;
const loopCount = 10;

// Avoid - shadows built-in
// let name = 'John';  // name is a global property
const userName = 'John';  // Better

Learn more

Dive deeper with these trusted resources:

MDNTutorialsPointW3Schools