<meta charset="utf-8">
<meta name="viewport" content="user-scalable=0, width=device-width, initial-scale=1.0, maximum-scale=1.0">
<div id="div" style="font-size:30px;height: 50px;">00:00:00</div>
<button onclick="begin()">开始</button>
<button onclick="record()">记录</button>
<button onclick="over()">结束</button>
<div id="record"></div>
<script>
var timer = "";
var result = "";
function begin() {
var div = document.getElementById("div");
var date = new Date().getTime();
timer = setInterval(function() {