小程序如何获取input标签的值

<scroll-view>
<view id='titleView'>
<text id="titleText">登录</text>
</view>
<view id='mainView'>
<text>用户名</text>
<input class='input' bindinput='usernameInput'></input>
<text>密码</text>
<input class='input' bindinput='passwordInput'></input>
<button class="btn" bindtap='login'>登录</button>
<button class='btn' bindtap='toRegister'>注册</button>
</view>
</scroll-view>

var app=getApp();
Page({
login:function(e){
<!--拼接url通过后台验证跳转
this.data.username获取标签中值-->
  var url = app.globalData.serverIp +"/user/login.html?"
  +"username="+this.data.username
  +"&password="+this.data.password;
  <!--为this赋值给全局对方法中调用-->
  var page=this;
  <!--用request进行后台传输-->
  wx.request({
    url: url,
    success:function(response){
      var serverData=response.data;
      var status=serverData.status;
      var msg="登录失败";
      if(status==200){
        msg="登录成功";
        //跳转商场首页navigateTo
        wx.navigateTo({
          url:"../storeindex/storeindex",
        })
         //把username保存到手机上
        //sync表示同步 setStorageSync函数的作用是同步保存数据相当于http中的cookie
        wx.setStorageSync("username", page.data.username);
      }
      wx.showToast({
        title: msg
      })
    },
    fail:function(e){
      console.log("联网失败");
      console.log(e);
    },
    
data: {
    username:"",
    password:""
  },
  usernameInput:function(e){
    this.data.username=e.detail.value;
  },
  passwordInput: function (e) {
    this.data.password = e.detail.value;
  },
  })
},