Thepop() method ofArray instances removes thelastelement from an array and returns that element. This method changes the length of thearray.

Try it

const plants = ["broccoli", "cauliflower", "cabbage", "kale", "tomato"];console.log(plants.pop());// Expected output: "tomato"console.log(plants);// Expected output: Array ["broccoli", "cauliflower", "cabbage", "kale"]plants.pop();console.log(plants);// Expected output: Array ["broccoli", "cauliflower", "cabbage"]

Syntax

pop()

Parameters

None.

Return value

The removed element from the array;undefined if the array is empty.

Description

Thepop() method removes the last element from an array and returns that value to the caller. If you callpop() on an empty array, it returnsundefined.

Array.prototype.shift() has similar behavior topop(), but applied to the first element in an array.

Thepop() method is a mutating method. It changes the length and the content ofthis. In case you want the value ofthis to be the same, but return a new array with the last element removed, you can usearr.slice(0, -1) instead.

Thepop() method isgeneric. It only expects thethis value to have alength property and integer-keyed properties. Although strings are also array-like, this method is not suitable to be applied on them, as strings are immutable.

Examples

Removing the last element of an array

The following code creates themyFish array containing four elements, thenremoves its last element.

const myFish = ["angel", "clown", "mandarin", "sturgeon"];const popped = myFish.pop();console.log(myFish); // ['angel', 'clown', 'mandarin' ]console.log(popped); // 'sturgeon'

Calling pop() on non-array objects

Thepop() method reads thelength property ofthis. If thenormalized length is 0,length is set to0 again (whereas it may be negative orundefined before). Otherwise, the property atlength - 1 is returned anddeleted.

const arrayLike = {  length: 3,  unrelated: "foo",  2: 4,};console.log(Array.prototype.pop.call(arrayLike));// 4console.log(arrayLike);// { length: 2, unrelated: 'foo' }const plainObj = {};// There's no length property, so the length is 0Array.prototype.pop.call(plainObj);console.log(plainObj);// { length: 0 }

Using an object in an array-like fashion

push andpop are intentionally generic, and we can use that to our advantage — as the following example shows.

Note that in this example, we don't create an array to store a collection of objects. Instead, we store the collection on the object itself and usecall onArray.prototype.push andArray.prototype.pop to trick those methods into thinking we're dealing with an array.

const collection = {  length: 0,  addElements(...elements) {    // obj.length will be incremented automatically    // every time an element is added.    // Returning what push returns; that is    // the new value of length property.    return [].push.call(this, ...elements);  },  removeElement() {    // obj.length will be decremented automatically    // every time an element is removed.    // Returning what pop returns; that is    // the removed element.    return [].pop.call(this);  },};collection.addElements(10, 20, 30);console.log(collection.length); // 3collection.removeElement();console.log(collection.length); // 2

Specifications

Browser compatibility

See also

• Indexed collections guide
• Array
• Array.prototype.push()
• Array.prototype.shift()
• Array.prototype.unshift()
• Array.prototype.concat()
• Array.prototype.splice()