Constant function.
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> Constant function.
A [constant function][constant-function] is a function whose output value is the same for every input value.
``bash`
npm install @stdlib/utils-constant-function
`javascript`
var constantFunction = require( '@stdlib/utils-constant-function' );
#### constantFunction( x )
Returns a [constant function][constant-function] which always returns x.
`javascript
var fcn = constantFunction( 'beep' );
// returns
var v = fcn();
// returns 'beep'
v = fcn();
// returns 'beep'
`
- When provided an object reference, the returned function always returns the same reference.
`javascript
var obj = {};
var fcn = constantFunction( obj );
var bool = ( fcn() === obj );
// returns true
`
`javascript
var constantFunction = require( '@stdlib/utils-constant-function' );
var bool;
var fcn;
var arr;
var v;
var i;
fcn = constantFunction( 3.14 );
for ( i = 0; i < 10; i++ ) {
v = fcn();
// returns 3.14
}
arr = [ 1, 2, 3 ];
fcn = constantFunction( arr );
for ( i = 0; i < 10; i++ ) {
v = fcn();
bool = ( v === arr );
// returns true
}
`
*
- [@stdlib/utils-argument-function][@stdlib/utils/argument-function]: argument function.
- [@stdlib/utils-identity-function][@stdlib/utils/identity-function]: identity function.
*
This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].
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---
See [LICENSE][stdlib-license].
Copyright © 2016-2026. The Stdlib [Authors][stdlib-authors].
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[constant-function]: https://en.wikipedia.org/wiki/Constant_function
[@stdlib/utils/argument-function]: https://www.npmjs.com/package/@stdlib/utils-argument-function
[@stdlib/utils/identity-function]: https://www.npmjs.com/package/@stdlib/utils-identity-function