html5 有两种缓存
1、localStorage：浏览器关闭后，数据库还存在。
2、sessionStorage：session缓存，浏览器关闭后，数据已经不存在。
实例一：localStorage
<!DOCTYPE HTML>
<html>
<body>
<script type="text/javascript">
if (localStorage.pagecount)
{
localStorage.pagecount=Number(localStorage.pagecount) +1;
}
else
{
localStorage.pagecount=1;
}
document.write("Visits "+ localStorage.pagecount + " time(s).");
</script>
</body>
</html>实例二：sessionStorage
<!DOCTYPE HTML>
<html>
<body>
<script type="text/javascript">
if (sessionStorage.pagecount)
{
sessionStorage.pagecount=Number(sessionStorage.pagecount) +1;
}
else
{
sessionStorage.pagecount=1;
}
document.write("Visits "+ sessionStorage.pagecount + " time(s).");
</script>
</body>
</html>
