function getElementsByClassName(className, tag, elm){
  var testClass = new RegExp("(^|\\s)" + className + "(\\s|$)");
  var tag = tag || "*";
  var elm = elm || document;
  var elements = (tag == "*" && elm.all)? elm.all : elm.getElementsByTagName(tag);
  var returnElements = [];
  var current;
  var length = elements.length;
  for(var i=0; i<length; i++){
    current = elements[i];
    if(testClass.test(current.className)){
      returnElements.push(current);
    }
  }
  return returnElements;
}


function pageWidth() {return window.innerWidth != null? window.innerWidth: document.body != null? document.body.clientWidth:null;}
function pageHeight() {return window.innerHeight != null? window.innerHeight: document.body != null? document.body.clientHeight:null;}