用原生JS写点名器

点名器

var oBtn = document.getElementById("btn");
    var oCon = document.getElementById("con");
    var names = ["陈纪法","张三","李四","胡宝林","柏洪洋"];
    var flag = true;//保存当前停止状态
    var timer = null;
    oBtn.onclick=function () {
        if (flag){
            oBtn.innerHTML="stop"
            timer=setInterval(function () {
                oCon.innerHTML=names[Math.floor(Math.random()*names.length)]
            },30)
        }else {
            clearInterval(timer)
            oBtn.innerHTML="start"
        }
        flag=!flag

    }