Array.prototype.shift()

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

Syntax

arr.shift()

Return value

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

Description

The shift method removes the element at the zeroeth index and shifts the values at consecutive indexes down, then returns the removed value. If the length property is 0, undefined is returned.

shift is intentionally generic; this method can be called or applied to objects resembling arrays. Objects which do not contain a length property reflecting the last in a series of consecutive, zero-based numerical properties may not behave in any meaningful manner.

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

Examples

Removing an element from an array

The following code displays the myFish array before and after removing its first element. It also displays the removed element:

var myFish = ['angel', 'clown', 'mandarin', 'surgeon'];

console.log('myFish before:', JSON.stringify(myFish));
// myFish before: ['angel', 'clown', 'mandarin', 'surgeon']

var shifted = myFish.shift();

console.log('myFish after:', myFish);
// myFish after: ['clown', 'mandarin', 'surgeon']

console.log('Removed this element:', shifted);
// Removed this element: angel

Using shift() method in while loop

The shift() method is often used in condition inside while loop. In the following example every iteration will remove the next element from an array, until it is empty:

var names = ["Andrew", "Edward", "Paul", "Chris" ,"John"];

while( (i = names.shift()) !== undefined ) {
    console.log(i);
}
// Andrew, Edward, Paul, Chris, John

Specifications

Specification
ECMAScript (ECMA-262)
The definition of 'Array.prototype.shift' in that specification.

Browser compatibility

DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
shiftChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 5.5Opera Full support 4Safari Full support 1WebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support 10.1Safari iOS Full support 1Samsung Internet Android Full support 1.0nodejs Full support 0.1.100

Legend

Full support
Full support

See also