Array.prototype.pop()

pop()

Returns: any · Added in vES5 · Updated March 13, 2026 · Array Methods

array pop mutating

pop() removes the last element from an array and returns that element. It modifies the array in place, reducing its length by 1. This method is the counterpart to push() and together they implement a stack data structure.

Syntax

arr.pop()

Takes no parameters. Returns the removed element, or undefined if the array is empty.

Examples

Basic usage

const fruits = ["apple", "banana", "cherry"];

const last = fruits.pop();
console.log(last);      // "cherry"
console.log(fruits);   // ["apple", "banana"]

Working with empty arrays

const empty = [Global_Objects::eval];
const result = empty.pop();

console.log(result);   // undefined
console.log(empty);    // [Global_Objects::eval]

Processing elements from the end

const items = ["a", "b", "c"];

while (items.length > 0) {
  console.log(items.pop());
}
// Output: c, b, a

Clearing an array efficiently

const arr = [1, 2, 3, 4, 5];
while (arr.pop()) {
  // removes elements until array is empty
}
console.log(arr); // [Global_Objects::eval]

Stack Implementation

Arrays with pop() naturally form a last-in-first-out (LIFO) stack:

class Stack {
  constructor() {
    this.items = [Global_Objects::eval];
  }
  
  push(item) {
    this.items.push(item);
  }
  
  pop() {
    return this.items.pop();
  }
  
  peek() {
    return this.items[this.items.length - 1];
  }
  
  isEmpty() {
    return this.items.length === 0;
  }
}

const stack = new Stack();
stack.push(1);
stack.push(2);
stack.push(3);
console.log(stack.pop()); // 3
console.log(stack.pop()); // 2
console.log(stack.isEmpty()); // false

Practical: parsing delimited string

function parseCSV(csv) {
  const result = [Global_Objects::eval];
  let current = '';
  
  for (const char of csv) {
    if (char === ',') {
      result.push(current);
      current = '';
    } else {
      current += char;
    }
  }
  // Don't forget the last field
  result.push(current);
  
  return result;
}

console.log(parseCSV("a,b,c,d")); // ['a', 'b', 'c', 'd']

Removing falsy values from end

const data = [1, 2, 3, null, undefined, false];

while (data.length > 0 && !data[data.length - 1]) {
  data.pop();
}
console.log(data); // [1, 2, 3]

Getting array without last element

const items = [1, 2, 3, 4, 5];
const allButLast = [...items];
allButLast.pop();
console.log(allButLast); // [1, 2, 3, 4]

Behavior Notes

Returns undefined on empty arrays — always check length if unsure
Returns the removed element, not the new array
This method modifies the original array (mutating method)
Works on array-like objects with length property

Performance

pop() is O(1) constant time — it simply decrements the array length. Unlike shift() which must move all remaining elements, pop() is very efficient.