JavaScript - Delete Operator

Overview

Estimated time: 10–15 minutes

delete removes properties from objects. It does not affect local variables or function parameters.

Learning Objectives

• Remove properties using delete obj.key or delete obj['key'].
• Know when delete has no effect.

Prerequisites

• JavaScript - typeof Operator

Examples

const user = { id: 1, name: 'Ada' };
delete user.name; // removes name

function f(x){
  // delete x; // has no effect on local variables
}

Common Pitfalls

• Deleting array indices leaves holes; prefer methods like splice for arrays.
• delete on non-configurable properties fails silently (or throws in strict mode).