<form >
      <ul>
        <li><p>用户名</p></li>
        <li><input type="text" name="username" id="username"></li>
      </ul>
      <ul>
        <li><p>密码</p></li>
        <li><input type="password" name="password" id="password"></li>
      </ul>
      <ul class="mt50">
        <li><input id="login_submit" class="submit" type="button" value="登 陆"></li>
      </ul>
    </form>

$("#login_submit").click(function(){
  var username=$('#username').val();
  var password=$('#password').val();
  //这里实现对 username和password格式的判断
  //........
  //发送ajax请求 使用post方式发送json字符串给后台login
  $.ajax({
    type: "post",
    url: "http://localhost:3000/login",
    dataType: "json",
    data:{ username: username, password: password },
    success: function(data){
    //接受返回的数据，前端判断采取的动作
      if(data){
        if(data.message=="false"){
          alert('密码错误，请重新输入');
          window.location.href="login";
        }else{
          alert('登陆成功');
          window.location.href="index";
        }
      } else{
      }
    }
  });
});

/**
 * 注册页 post 
 */
router.post('/reg', function (req, res, next) {
  //先查询有没有这个user
  console.log("req.body"+req.body);
  user2.findDocuments(DATABASE, "users", 1, {"uName":req.body.username}, function (user) {
    res.setHeader('Content-Type', 'application/json;charset=utf-8');
    if(user.length==0){
      //用户名没有重复 同意创建用户
      user2.insertDocuments(DATABASE, "users",
        [{
          "uName":req.body.username,
          "uPasswd":req.body.password,
          "uEmail":req.body.email,
          "uHasshop":0,
          "uShopname":"null",
          "aId":'-1'

        }],
        function (result){
          res.send({status:"success", message:"true"});
        }
      );
    }
    else{
      // 用户名重复。找到这个user 不同意创建用户
      res.send({status:"success", message:"false"});
    }
  });
});