Array.prototype.indexOf = function(el, start) {
    var start = start || 0;
    for ( var i=0; i < this.length; ++i ) {
        if ( this[i] === el ) {
            return i;
        }
    }
    return -1;
};

function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      if (oldonload) {
        oldonload();
      }
      func();
    }
  }
}