课外扩展问题

请告诉我这个可以如何用代码实现，慕课网的效果

我测试用的代码：（我认为可以结合这个测试）

// JavaScript Document
	//封装创建事件的函数
	function addHandler(element, type, handler) {
    	if (element.addEventListener) {
        	element.addEventListener(type, handler, true);
    	}
    	else if (element.attachEvent) {
       		element.attachEvent('on' + type, handler);
    	}
    	else {
       		element['on' + type] = handler;
    	}
		}
	var screen={
		".screen-1":[".screen-1_h2",".screen-1_h3"],
		".screen-2":[".screen-2_h2",".screen-2_h3",".screen-2_line",".screen-2_people",".screen-2_cloud",".screen-2_plane"],
		".screen-3":[".screen-3_h2",".screen-3_smallbox_up_line",".screen-3_h3",".screen-3_left",
					 ".screen-3_smallbox_down1",".screen-3_smallbox_down2",".screen-3_smallbox_down3",
					 ".screen-3_smallbox_down4",".screen-3_smallbox_down5"],
		".screen-4":[".screen-4_h2",".screen-4_h3",".screen-4_line",
					 ".screen-4_smallbox1",".screen-4_smallbox2",".screen-4_smallbox3",".screen-4_smallbox4"],
		".screen-5":[".screen-5_people",".screen-5_h2",".screen-5_h3",".screen-5_line"]
	};
	function animate(ele){
		var screenele=screen[ele];//对象里面的screen1-5
		var target=document.querySelector(ele);
		var isSetAnimateClass = false; // 是否有初始化子元素的样式
  		var isAnimateDone = false; // 当前屏幕下所有子元素的状态是DONE？
		addHandler(target,"click",function(){
			if(isSetAnimateClass==false){//  初始化样式，增加init A A_init
				for(var i=0;i<screenele.length;i++){
					var screenanimate=document.querySelector(screenele[i]);//对象里面的screen1-5数组里的每一项
					var classscreen=screenanimate.getAttribute("class");
					screenanimate.setAttribute('class',classscreen +' '+screenele[i].substr(1)+'_animate_init');
				}
				isSetAnimateClass = true;
        		return ;
			}
			if(isAnimateDone == false){//切换所有 animateElements 的  init -> done   A A_done
			   for(var i=0;i<screenele.length;i++){
					var screenanimate=document.querySelector(screenele[i]);//对象里面的screen1-5数组里的每一项
					var classscreen=screenanimate.getAttribute("class");
					screenanimate.setAttribute('class',classscreen.replace('_animate_init','_animate_done'));
				}
				isAnimateDone = true;
        		return ;
			}
			if(isAnimateDone == true){//切换所有 animateElements 的  done -> init   A A_init
			   for(var i=0;i<screenele.length;i++){
					var screenanimate=document.querySelector(screenele[i]);//对象里面的screen1-5数组里的每一项
					var classscreen=screenanimate.getAttribute("class");
					screenanimate.setAttribute('class',classscreen.replace('_animate_done','_animate_init'));
				}
				isAnimateDone = false;
        		return ;
			}
		});
	}
	for(k in screen){animate(k);}