原生JavaScript实现登录页记住密码功能详解

window.onload = function(){
 var oForm = document.getElementById('myForm');
 var oUser = document.getElementById('username');
 var oPswd = document.getElementById('passwrod');
 var oRemember = document.getElementById('remember');
 //页面初始化时，如果帐号密码cookie存在则填充
 if (getCookie('username') && getCookie('password')) {
 oUser.value = getCookie('username');
 oPswd.value = getCookie('password');
 oRemember.checked = true;
 }
 //复选框勾选状态发生改变时，如果未勾选则清除cookie
 oRemember.onchange = function() {
 if (!this.checked) {
  delCookie('username');
  delCookie('password');
 }
 };
 //表单提交事件触发时，如果复选框是勾选状态则保存cookie
 oForm.onsubmit = function() {
 if (remember.checked) {
  setCookie('username', oUser.value, 7); //保存帐号到cookie，有效期7天
  setCookie('password', oPswd.value, 7); //保存密码到cookie，有效期7天
 }
 };
};
//设置cookie
function setCookie(name, value, day) {
 var date = new Date();
 date.setDate(date.getDate() + day);
 document.cookie = name + '=' + value + ';expires=' + date;
};
//获取cookie
function getCookie(name) {
 var reg = RegExp(name + '=([^;]+)');
 var arr = document.cookie.match(reg);
 if (arr) {
 return arr[1];
 } else {
 return '';
 }
};
//删除cookie
function delCookie(name) {
 setCookie(name, null, -1);
};

<form id="myForm" action="login" method="post">
 <input type="text" value="" class="inp" name = "username" id="username" />
 <input type="password" value="" class="inp" name = "password" id="passwrod" />
 
 <input type="text" class="inp" id="yzm" placeholder="验证码" />
 <img id="img" src="getCode" onclick="changeImg()">
 
 <div style="margin: 10px;">
 <span><input type="checkbox" id="remember"><label for="remember">记住我</label></span>
 <span style="float: right;">注册</span>
 </div>
 
 <button type="button" class="inp" id="btn">立即登录</button>
</form>