JavaScript Function Parameters

Rest Parameters

Collect remaining arguments:

function sum(first, ...rest) {
  return first + rest.reduce((a, b) => a + b, 0);
}

sum(1, 2, 3, 4); // 10

Default Parameters

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

Parameter Destructuring

function displayUser({ name, age }) {
  console.log(`${name} is ${age}`);
}

displayUser({ name: 'John', age: 25 });

Key Takeaway

Rest collects arguments. Defaults provide fallbacks. Destructuring extracts from objects. Powerful parameter features.