## 1.onbeforeunload 方法實現監聽頁面停留時間
```
var dt1 = new Date();
window.onbeforeunload = function(){
var dt2 = new Date();
var ms = dt2.getTime() - dt1.getTime();
}
```
## 2.解決微信iphone onbeforeunload 失效
```
<html>
<head>
<meta charset="UTF-8">
<title>123</title>
</head>
<body>
<div id="a"></div>
<script>
const KEY = 'duration';
let start = 0; // 記錄開始時間
const data = localStorage.getItem(KEY); // 讀取本地已經記錄的時間
document.querySelector('#a').innerHTML = data || '空';
window.addEventListener('load', function() {
start = Date.now();
}, false);
window.addEventListener('unload', function() {
const duration = Date.now() - start;
localStorage.setItem(KEY, duration.toString());
}, false);
</script>
</body>
</html>
```
## 3.iphone不支持onbeforeunload
```
window.addEventListener("pageshow", myLoadHandler, false);
window.addEventListener("pagehide", myUnloadHandler, false);
function myLoadHandler(evt)
{
if (evt.persisted) {
// This is actually a pageshow event and the page is coming out of the Page Cache.
// Make sure to not perform the "one-time work" that we'd normally do in the onload handler.
...
return;
}
// This is either a load event for older browsers,
// or a pageshow event for the initial load in supported browsers.
// It's safe to do everything my old load event handler did here.
...
}
function myUnloadHandler(evt)
{
if (evt.persisted) {
// This is actually a pagehide event and the page is going into the Page Cache.
// Make sure that we don't do any destructive work, or work that shouldn't be duplicated.
...
return;
}
// This is either an unload event for older browsers,
// or a pagehide event for page tear-down in supported browsers.
// It's safe to do everything my old unload event handler did here.
...
}
if ("onpagehide" in window) {
window.addEventListener("pageshow", myLoadHandler, false);
window.addEventListener("pagehide", myUnloadHandler, false);
} else {
window.addEventListener("load", myLoadHandler, false);
window.addEventListener("unload", myUnloadHandler, false);
}
```
