Array.prototype.shift()

Overview.

The Array.prototype.shift() method removes the first element from an array and returns that removed element. This method changes the length of the array.

Syntax

array.shift();

Parameters

No paramter.

return value

The return value of the shift() method is the element that was removed from the array. If the array is empty, undefined is returned.

Examples

const numbers = [1, 2, 3, 4, 5];
const firstNumber = numbers.shift();
// firstNumber is 1
// numbers is now [2, 3, 4, 5]

const fruits = ["banana", "apple", "orange"];
const firstFruit = fruits.shift();
// firstFruit is 'banana', fruits is now ['apple', 'orange']

const emptyArray = [];
const removedElement = emptyArray.shift();
// removedElement is undefined, emptyArray is still []

Use cases

Here are some use cases with examples for the shift() method:

Removing the first element of an array:

const array = [1, 2, 3, 4, 5];
const firstElement = array.shift();
console.log(array); // Output: [2, 3, 4, 5]
console.log(firstElement); // Output: 1

Implementing a queue:

const queue = [1, 2, 3];
const dequeuedElement = queue.shift();
console.log(queue); // Output: [2, 3]
console.log(dequeuedElement); // Output: 1
queue.push(4);
console.log(queue); // Output: [2, 3, 4]

Creating a circular buffer:

const buffer = [1, 2, 3];
const removedElement = buffer.shift();
buffer.push(4);
console.log(buffer); // Output: [2, 3, 4]
console.log(removedElement); // Output: 1

Notes

The shift() method changes the original array, it doesn't return a new array.
If you only want to get the first element of an array without removing it, you can use the index notation, like this: const firstElement = array[0];

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