html 页面

用户名:<input type="text" id="username" name=""><br>密码:&nbsp;&nbsp;<input type="password" id="userpwd" name=""><br>密码强度:<span id="mm"></span><br>验证码:<input type="text" id="yzm" name=""> <span id="testSpan"></span><br><input type="button" id="login" value="登录" name=""/>

JS代码块

var module = (function() {  var testSpan,msg,Slength,userpwd,userpwd,yzm;    function print(msg) {        alert(msg);    } ;//弹出消息框  //简单的验证码   function createyzm(testSpan,Slength){     var str = "0123456789qwertyuioplkjhgfdsazxcvbnmQWERTYUIOPLKJHGFDSAZXCVBNM";    var list = str.split("");    for (i = 0; i < Slength; i++)     {        var index = Math.floor(Math.random() * list.length);         testSpan.style.backgroundColor="#000";//验证码背景颜色         testSpan.style.color="#fff";//验证码颜色         testSpan.style.display="block";          testSpan.style.textAlign ="center";         testSpan.style.width="70px";//长度        testSpan.innerHTML += list[index];      }  return  testSpan.innerHTML;};function checkUserpwd(userpwd,errSpan) {        var numCount = (/[0-9]/g).test(userpwd) ? 1 : 0;        var lowCount = (/[a-z]/g).test(userpwd) ? 1 : 0;        var uppCount = (/[A-Z]/g).test(userpwd) ? 1 : 0;//二元运算符        switch (numCount + lowCount + uppCount) {            case 3:                errSpan.innerHTML = "强";                break;            case 2:                errSpan.innerHTML = "中";                break;            default:                errSpan.innerHTML = "弱";                break;                return true;    }};   function check(username,userpwd){          var uremeber = /^[a-zA-Z0-9_-]{4,16}$/;    var username=username.replace(" ","");    var userpwd=userpwd.replace(" ","");//去空格防止sql注入    if(username==""||userpwd=="")    {    print("用户名密码不能为空");    return false;    }    if(!uremeber.test(username)||!uremeber.test(userpwd)){        print("用户名密码为为4-16位但不限于(数字，字母，下划线)");        history.go(0);//刷新页面        return false;    }else  {        //...        return true;    }               };return {   checkUserpwd: checkUserpwd,//两个参数userpwd,errSpan errspan为提示密码强弱提示性文字，接受类型是js dom对象 注：jq对象用test方法,   // userpwd 为用户密码,   check: check,//用户名，密码，验证码    createyzm: createyzm,//testSpan,Slength 两个参数testSpan是验证码span标签dom类型对象,Slength是验证码长度    print: print//alert弹窗  };})();var yzm=module.createyzm(document.getElementById("testSpan"),4);document.getElementById("userpwd").onblur = function(){   module.checkUserpwd(this.value,document.getElementById('mm'));}document.getElementById("login").onclick=function(){    var a= module.check(document.getElementById("username").value,document.getElementById("userpwd").value);if(a==true ){    if(document.getElementById("yzm").value==yzm){        alert("登录成功！");    }else{        alert("验证码错误,请重新输入！");          history.go(0);//刷新页面        }    }}