Array Creation & Manipulation

• push(...items) → Adds elements to the end.
• pop() → Removes the last element.
• shift() → Removes the first element.
• unshift(...items) → Adds elements to the beginning.
• splice(start, deleteCount, item1, …) → Modifies the array by adding/removing elements.

let arr = [1, 2, 3, 4];
arr.splice(1, 2, "a", "b");
console.log(arr); // [1, "a", "b", 4]

• fill(value, start?, end?) → Fills elements with a specified value.

let numbers = [1, 2, 3];
numbers.fill(0);
console.log(numbers); // [0, 0, 0]

• reverse() → Reverses the array in place.

Array Access & Search

• length → Returns or sets the number of elements in an array.
• at(index) → Accesses an element using positive or negative index.

console.log([1, 2, 3].at(-1)); // 3

• includes(item) → Checks if an item exists in the array.
• indexOf(item) → Returns the index of the element (or -1 if not found).
• find(callback) → Returns the first matching element.
• findIndex(callback) → Returns the index of the first matching element.
• some(callback) → Checks if at least one element satisfies a condition.
• every(callback) → Checks if all elements satisfy a condition.