Parameters & Arguments in JavaScript
From the JavaScript cheat sheet · Functions · verified Jul 2026
Parameters & Arguments
Function parameters, defaults, rest, spread
javascript
// Default parameters
function greet(name = 'Guest') {
return `Hello, ${name}`;
}
// Rest parameters
function sum(...numbers) {
return numbers.reduce((a, b) => a + b);
}
// Spread arguments
const nums = [1, 2, 3];
sum(...nums);
// Destructuring parameters
function process({ name, age }) {
// use name and age
}💡 Default parameters can reference previous parameters
⚡ Rest parameters must be the last parameter
📌 Spread operator expands arrays into individual arguments
🔥 Arrow functions don't have arguments object, use rest parameters