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

Syntax

arr.shift()

Return value

The removed element.

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.

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: ' + 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"

Specifications

Specification Status Comment
ECMAScript 3rd Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.2.
ECMAScript 5.1 (ECMA-262)
The definition of 'Array.prototype.shift' in that specification.
Standard  
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'Array.prototype.shift' in that specification.
Standard  
ECMAScript 2017 Draft (ECMA-262)
The definition of 'Array.prototype.shift' in that specification.
Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 1.0 1.0 (1.7 or earlier) 5.5 (Yes) (Yes)
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (Yes) (Yes) (Yes) (Yes) (Yes) (Yes)

See also

Tag del documento e collaboratori

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 Ultima modifica di: eduardoboucas,