Spread & Rest Operators

let arr1 = [1, 2, 3];
let arr2 = [...arr1, 4, 5]; // Spread
console.log(arr2); // [1, 2, 3, 4, 5]

function sum(...nums) { // Rest
  return nums.reduce((a, b) => a + b, 0);
}
console.log(sum(5, 10, 15)); // 30

Explanation:

• ... (spread) copies values.
• ... (rest) collects multiple arguments.