Min/Max selection in javascript ( ruby style )

min_max.js

// Usage
// [1, 2, 3, 4].max() => 4
// [1, 2, 3, 4].min() => 1
//
// With blocks
// [1, 2, 3, 4].max( function(d){
//   return d*-1;
// }); => -1
//
// [1, 2, 3, 4].min( function(d){
//   return d*-1;
// }); => -4

if( Array.prototype.max === undefined ) {
  Array.prototype.max = function(block) {
    if( block === undefined || typeof(block) !== "function" ){
      block = function( e ){ return e; };
    }
    var max = block( this[0] );
    var len = this.length;
    for (var i = 1; i < len; i++) if (block( this[i] ) > max) max = block( this[i] );
    return max;
  }
}

if( Array.prototype.min === undefined ) {
  Array.prototype.min = function(block) {
    var min = block( this[0] );
    var len = this.length;
    for (var i = 1; i < len; i++) if (block( this[i] ) < min) min = block( this[i] );
    return min;
  }
}