About stdlib...
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.
The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.
When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.
To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!
Remove and return the first element of a collection.
npm install @stdlib/utils-shift
Alternatively,
- To load the package in a website via a
scripttag without installation and bundlers, use the ES Module available on theesmbranch (see README). - If you are using Deno, visit the
denobranch (see README for usage intructions). - For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the
umdbranch (see README).
The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.
To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
var shift = require( '@stdlib/utils-shift' );
Removes and returns the first element of a collection. A collection may be either an Array, Typed Array, or an array-like Object (i.e., an Object having a valid writable length property).
var arr = [ 1.0, 2.0, 3.0, 4.0, 5.0 ]; var out = shift( arr ); // returns [ [ 2.0, 3.0, 4.0, 5.0 ], 1.0 ] var bool = ( out[ 0 ] === arr ); // returns true var lastValue = out[ 1 ]; // returns 1.0
In contrast to Array.prototype.shift which returns only the removed element, the function also returns the shortened collection. For typed arrays having a length greater than 0, the returned collection is a new typed array view.
var Float64Array = require( '@stdlib/array-float64' ); var arr = new Float64Array( 2 ); arr[ 0 ] = 1.0; arr[ 1 ] = 2.0; var out = shift( arr ); // returns [ <Float64Array>[ 2.0 ], 1.0 ] var bool = ( out[ 0 ] === arr ); // returns false bool = ( out[ 0 ].buffer === arr.buffer ); // returns true var lastValue = out[ 1 ]; // returns 1.0
- When provided a typed array, the function does not change the underlying
ArrayBuffer. The function returns a new typed array view whose length is one less than the input typed array length. Accordingly, the function does not reduce the memory footprint of an input typed array.
var Float64Array = require( '@stdlib/array-float64' ); var shift = require( '@stdlib/utils-shift' ); var arr; var out; var i; arr = new Float64Array( 100 ); for ( i = 0; i < 100; i++ ) { out = shift( arr ); arr = out[ 0 ]; console.log( 'Length: %d', arr.length ); } console.log( arr );
@stdlib/utils-pop: remove and return the last element of a collection.@stdlib/utils-push: add one or more elements to the end of a collection.@stdlib/utils-unshift: add one or more elements to the beginning of a collection.
This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.
For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.
See LICENSE.
Copyright © 2016-2026. The Stdlib Authors.