Extending the native Array() class

You can see parts of this class in use in Configurable greeking and Using JS code libraries, part 2.

/*
  Code from "Developing Featherweight Web Services with JavaScript"
      http://feather.elektrum.org/
  (c)An Elektrum Press, retain this notice
      License: http://feather.elektrum.org/appendix/licenses.html
*/

Array.prototype.serial = function () {
  switch( this.length ) {
    case 0 : return false;
    case 1 : return this[0].toString();
    case 2 : return this.join(' and ');
    default: return this.slice(0,-1).join(', ') +
               ', and ' + this[ this.length - 1 ];
  }
}

Array.prototype.sum = function () {
  var sum = 0;
  for ( var i = 0; i < this.length; i++ ) sum += this[i];
  return sum;
}

Array.prototype.isIn = function ( what ) {
  if ( ! what ) return false;
  for ( var i = 0; i < this.length; i++ ) {
    if ( this[i] == what ) return true;
  }
  return false;
}

Array.prototype.dedup = function () {
  var newArray = new Array ();
  var seen = new Object ();
  for ( var i = 0; i < this.length; i++ ) {
    if ( seen[ this[i] ] ) continue;
    newArray.push( this[i] );
    seen[ this[i] ] = 1;
  }
  return newArray;
}

Array.prototype.max = function () {
  var max = new Number();
  for ( var i = 0; i < this.length; i++ ) {
    if ( this[i] > max ) max = this[i];
  }
  return max;
}

Array.prototype.min = function () {
  var min = new Number();
  for ( var i = 0; i < this.length; i++ ) {
    if ( this[i] < min ) min = this[i];
  }
  return min;
}

Array.prototype.mean = function () {
  return this.sum() / this.length;
}

Live tests

« Extending the native String() class · Extending the native Number() class »