【JavaScript-28】js的例子点名器，注释咔咔全

<script type="text/javascript">

		
		var btn = document.querySelector(".top button");
		var lock = true;

		//实现动态点名
		//点击按钮
				btn.onclick = function() {
    			//如果lock为true
    			if (lock) {
        			btn.innerHTML = '停止点名';
       				times = setInterval( function (){
		 			var spans = document.querySelectorAll(".content span");
					
					for(var i =0;i<spans.length;i++){
						spans[i].index = i;
						// spans[0].className = "active";
						spans[i].className = "";
					}
						num = Math.floor(Math.random()*i); 
						spans[num].className = "active";
						console.log("num",num);
						//max-min+1 +min
						//获取到了随机的i
						//如果最后获取的内容不等于空
		
				},500);
       				if(document.querySelector('.active') != null){
       					document.querySelector('.active').remove();
						// spans[0].className = "active";
       				}
       				
   				 } else {
        			btn.innerHTML = '开始';
        			//清除定时器
       			 	clearInterval(times);
        			
   				 }
   				 //取反
    			lock = !lock;
				}
	script>