初识localStorage
1.localStorage是什么
localStorage 也是一种浏览器存储数据的方式（本地存储），它只是存储在本地，不会发送到服务器端
单个域名下的localStorage总大小有限制
2.在浏览器中操作localStorage
3.localStorage的基本用法
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>初始localStorage</title>
</head>
<body>
<script>
//console.log(localStorage)
//setItem（）存储数据
localStorage.setItem('username','lyw');
localStorage.setItem('username','yth');
localStorage.setItem('age',18);
localStorage.setItem('sex','nv');
//length
//console.log(localStorage.length)
//getItem
/* console.log(localStorage.getItem('username'));
console.log(localStorage.getItem('age'));
console.log(localStorage.getItem('sex')); */
//获取不存在的返回null
console.log(localStorage.getItem('name'));
//console.log(localStorage);
//removeItem
/* localStorage.removeItem('username');
localStorage.removeItem('age');
//删除不存在的key，不报错
localStorage.removeItem('name'); */
//clear（）
localStorage.clear();
console.log(localStorage)
</script>
</body>
</html>
localStorage实现自动填充
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>初始localStorage</title>
</head>
<body>
<script>
//console.log(localStorage)
//setItem（）存储数据
localStorage.setItem('username','lyw');
localStorage.setItem('username','yth');
localStorage.setItem('age',18);
localStorage.setItem('sex','nv');
//length
//console.log(localStorage.length)
//getItem
/* console.log(localStorage.getItem('username'));
console.log(localStorage.getItem('age'));
console.log(localStorage.getItem('sex')); */
//获取不存在的返回null
console.log(localStorage.getItem('name'));
//console.log(localStorage);
//removeItem
/* localStorage.removeItem('username');
localStorage.removeItem('age');
//删除不存在的key，不报错
localStorage.removeItem('name'); */
//clear（）
localStorage.clear();
console.log(localStorage)
</script>
</body>
</html>
localStorage的注意事项
1.localStorage的存储期限
localStorage是持久化的本地存储，除非手动清除（比如通过js删除，或者清除浏览器缓存），否则数据是永远不会过期的
sessionStorage（用法和localStorage一样只不过sessionStorage是会话存储）
当会话结束（比如关闭浏览器）的时候，sessionStorage中的数据会被清空
2.localStorage 键和值的类型
localStorage存储的是键和值只能是字符串类型
不是字符串类型，也会转化成字符串类型再存进去
3.不同域名下能否共用localStorage
不同域名是不能共用localStorage的
4.localStorage的兼容性
IE7及以下版本不支持localStorage，IE8 开始支持