noneByRight

    Test whether all elements in a collection fail a test implemented by a predicate function, iterating from right to left.

    Usage

    var noneByRight = require( '@stdlib/utils/none-by-right' );
    

    noneByRight( collection, predicate[, thisArg ] )

    Tests whether all elements in a collection fail a test implemented by a predicate function, iterating from right to left.

    function isPositive( value ) {
        return ( value > 0 );
    }
    
    var arr = [ -1, -2, -3, -4 ];
    
    var bool = noneByRight( arr, isPositive );
    // returns true
    

    If a predicate function returns a truthy value, the function immediately returns false.

    function isPositive( value ) {
        return ( value > 0 );
    }
    
    var arr = [ -1, 2, -3, -4 ];
    
    var bool = noneByRight( arr, isPositive );
    // returns false
    

    The invoked function is provided three arguments:

    • value: collection element
    • index: collection index
    • collection: input collection

    To set the function execution context, provide a thisArg.

    function sum( value ) {
        if ( value < 0 ) {
            return true;
        }
        this.sum += value;
        this.count += 1;
        return false;
    }
    
    var arr = [ 1, 2, 3, 4 ];
    
    var context = {
        'sum': 0,
        'count': 0
    };
    
    var bool = noneByRight( arr, sum, context );
    // returns true
    
    var mean = context.sum / context.count;
    // returns 2.5
    

    Notes

    • A collection may be either an Array, Typed Array, or an array-like Object (excluding strings and functions).

    • If provided an empty collection, the function returns true.

      function truthy() {
          return true;
      }
      var bool = noneByRight( [], truthy );
      // returns true
      
    • The function does not skip undefined elements.

      function log( value, index ) {
          console.log( '%s: %s', index, value );
          return false;
      }
      
      var arr = [ 1, , , 4 ];
      
      var bool = noneByRight( arr, log );
      /* =>
          3: 4
          2: undefined
          1: undefined
          0: 1
      */
      
    • The function provides limited support for dynamic collections (i.e., collections whose length changes during execution). Note, however, that index incrementation is not guaranteed to be monotonically decreasing.

    Examples

    var randu = require( '@stdlib/random/base/randu' );
    var noneByRight = require( '@stdlib/utils/none-by-right' );
    
    function isPositive( value ) {
        return ( value > 0 );
    }
    
    var bool;
    var arr;
    var i;
    
    arr = new Array( 100 );
    for ( i = 0; i < arr.length; i++ ) {
        arr[ i ] = -randu();
    }
    
    bool = noneByRight( arr, isPositive );
    // returns true