Constant Function

Constant function.

A constant function is a function whose output value is the same for every input value.

Installation

npm install @stdlib/utils-constant-function

Usage

var constantFunction = require( '@stdlib/utils-constant-function' );

constantFunction( x )

Returns a constant function which always returns x.

var fcn = constantFunction( 'beep' );
// returns <Function>

var v = fcn();
// returns 'beep'

v = fcn();
// returns 'beep'

Notes

• When provided an object reference, the returned function always returns the same reference.

  var obj = {};
  var fcn = constantFunction( obj );
  
  var bool = ( fcn() === obj );
  // returns true

Examples

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
}

See Also

• @stdlib/utils-argument-function: argument function.
• @stdlib/utils-identity-function: identity function.

Notice

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.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.