cookie——登录注册极简版

本实例旨在最直观地说明如何利用cookie完成登录注册功能，忽略正则验证。

index.html

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        a {
            color: red;
        }
    </style>
</head>
<body>
我是首页<br />
<img src="https://ss1.bdstatic.com/70cFvXSh_Q1YnxGkpoWK1HF6hhy/it/u=1955082529,2126835222&fm=117&gp=0.jpg" alt="">
<p>内容不错？去<a href="register.html">注册</a></p>
<p>已有账号？直接<a href="login.html">登录</a></p>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        a {
            color: red;
        }
    </style>
</head>
<body>
<form action="" method="get">
    <input type="text" placeholder="用户名"><br /><input type="password" placeholder="密码"><br />
    <input type="button" value="登录">
    <p>没有账号？去<a href="register.html">注册</a></p>
</form>

<script src="cookie.js"></script>
<script>
    var oBtn = document.getElementsByTagName('input');
    oBtn[2].onclick = function(){
        if(getCookie(oBtn[0].value) && getCookie(oBtn[0].value) == oBtn[1].value){//该账号存在且密码正确
            alert('登陆成功!');
            location.href = 'index.html';
        }else{
            alert('登录名或密码有误');
        }
    }
</script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        a {
            color: red;
        }
    </style>
</head>
<body>
<form action="" method="get">
    <input type="text" placeholder="用户名"><br /><input type="password" placeholder="密码"><br />
    <input type="button" value="注册">
    <p>已有账号？直接<a href="login.html">登录</a></p>
</form>

<script src="cookie.js"></script>
<script>
    var oBtn = document.getElementsByTagName('input');
    oBtn[2].onclick = function(){
        if(getCookie(oBtn[0].value)){
            alert('用户名已存在');
            oBtn[0].value = oBtn[1].value = '';
        }else{
            createCookie(oBtn[0].value,oBtn[1].value,30);
            alert('注册成功!跳转至登录页面?');
            location.href = "login.html";
        }
    };
</script>
</body>
</html>

cookie.js

//创建cookie
function createCookie(key,value,expires,domain,secure){
    var cookieText = encodeURIComponent(key) + "=" + encodeURIComponent(value) + ";path=/";
    if(!isNaN(expires)){
        if(typeof expires == "number" && expires > 0){
            var date = new Date();
            date.setDate(date.getDate() + expires);
            cookieText += ";expires=" + date;
        }
    }
    if(domain){
        cookieText += ";domain=" + domain;
    }
    if(secure){
        cookieText += ";secure";
    }
    document.cookie = cookieText;
}

//获取cookie
function getCookie(key){
    var keyText = encodeURIComponent(key) + "="
    var start = document.cookie.indexOf(keyText); //找到开始位置
    if(start != -1){
        var end = document.cookie.indexOf(";",start); //找到结束位置
        if(end == -1){
            end = document.cookie.length;
        }
        var cookieValue = decodeURIComponent(document.cookie.substring(start + keyText.length,end));
    }
    return cookieValue;
}

//删除cookie
function removeCookie(key){
    document.cookie = key + "=;expires=" + new Date(0) + ";path=/";
}

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原文地址：https://www.cnblogs.com/LLLLily/p/7354406.html