JavaScript Default Parameters

Setting Default Values

Provide fallback values for parameters.

function greet(name = 'Guest') {
  return `Hello, ${name}!`;
}

greet();        // "Hello, Guest!"
greet('John');  // "Hello, John!"

Multiple Defaults

function createUser(name, age = 18, isActive = true) {
  return { name, age, isActive };
}

Key Takeaway

Default parameters provide fallback values. Use when parameter might be undefined. Makes functions more flexible.