客户端储存数据
1.两种方式:
a.localStorage - 没有时间限制的数据储存
b.sessionStorage - 针对一个session的数据存储 有时间限定，浏览器关闭
2.与cookie对比：
之前都是cookie存储，但cookie不适合大量数据的存储，因为他们由每个对服务器的请求来传递，这使得cookie速度很慢而且效率不高
localStorage
.html文件
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<script src="localStorage.js"></script>
</head>
<body>
<textarea style="width: 200px; height: 200px;" id="ta"></textarea>
<button id="btn">save</button>
</body>
</html>
localStorage.js文件
var ta;
var btn;
window.onload = function(){
ta = document.getElementById("ta");
if(localStorage.text){
ta.value = localStorage.text;
}
btn = document.getElementById("btn");
btn.onclick = function(){
//alert(ta.value);
localStorage.text = ta.value;
}
}
sessionStorage
.html文件
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
<script src="sessionStorage.js"></script>
</head>
<body>
<span id="txt">0</span>
<button id="addbtn">Add</button>
</body>
</html>
sessionStorage.js文件
var num = 0;
var txt;
var btn;
window.onload = function(){
txt = document.getElementById("txt");
btn = document.getElementById("addbtn");
if(sessionStorage.num){
num = sessionStorage.num;
}else{
num = 0;
}
btn.onclick = function(){
num++;
sessionStorage.num = num;
showNum();
}
}
function showNum(){
txt.innerHTML = num;
}
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