How do I use rest parameters in JavaScript?

How do I use rest parameters in JavaScript?

Rest parameters allow you to represent an indefinite number of arguments as an array. You can use them by adding '...' before the parameter name in a function.

Can you show me an example?

Sure! Here's a simple example:

function sum(...numbers) {
    return numbers.reduce((acc, curr) => acc + curr, 0);
}
console.log(sum(1, 2, 3, 4)); // Output: 10

What if I want to combine rest parameters with other parameters?

You can mix rest parameters with regular parameters. Just make sure the rest parameter is the last one in the function definition. For example:

function multiply(factor, ...numbers) {
    return numbers.map(num => num * factor);
}
console.log(multiply(2, 1, 2, 3)); // Output: [2, 4, 6]