document.getElementsByClassName = function(cl) {
	var retnode = [];
	var myclass = new RegExp('\\b'+cl+'\\b');
	var elem = this.getElementsByTagName('*');
	for (var i = 0; i < elem.length; i++) {
		var classes = elem[i].className;
		if (myclass.test(classes)) retnode.push(elem[i]);
	}
	return retnode;
};
 
function collapse(targetname){
	var divs=document.getElementsByClassName(targetname);
	for(i=0;i<divs.length;i++){
		if(divs[i].style.display==''){
			divs[i].style.display='none'
		}else{
			divs[i].style.display=''
		}
	}
}