/**
 * Index of operation for arrays. Required for the article sliders. 
 * @see https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Array/indexOf
 */
if (!Array.prototype.indexOf) {
  Array.prototype.indexOf = function(elt /*, from*/) {
    var len = this.length >>> 0;
/*
    var from = Number(arguments[1]) || 0;
    from = (from < 0)
         ? Math.ceil(from)
         : Math.floor(from);
    if (from < 0)
      from += len;
*/ 
    for (var from = 0; from < len; from++) {
      if (from in this && this[from] === elt)
        return from;
    }
    return -1;
  };
}