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stdlib/lib/node_modules/@stdlib/utils/constant-function at develop · stdlib-js/stdlib

Constant function.

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

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