Document = document.constructor;
HTMLElement = document.createElement("x").constructor;
Document.prototype.getElementsByClassName = HTMLElement.prototype.getElementsByClassName = function(className, tag) {
	var classElements = new Array();
	var els = this.getElementsByTagName(tag);
	var elsLen = els.length;
	var pattern = new RegExp("(^|\\s)" + className + "(\\s|$)");;
	for (i = 0, j = 0; i < elsLen; i++) {
		if ( pattern.test(els[i].className) ) {
		  classElements[j] = els[i];
		  j++;
		}
	}
	return classElements;
}
function showBy(id){
elem = document.getElementsByClassName('shopBy', 'div');
for(i=0;i<elem.length;i++){
elem[i].style.display = 'none';
}
document.getElementById(id).style.display = 'block';
}