Constant Function

    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
    }