聚合物不改变定义特性的值

Question

I am using digits-api for login. I am initializing the script on attach using attached life cycle event.

attached: function(){
         console.log("Attached")
         Digits.init({ consumerKey: '************' });
        }

Then On clicking the Button it user can login.

onLoginButtonTap : function(){
        Digits.logIn().done(this.onLogIn).fail(this.onFail);
        },

When the user successfully login it will go to onLogIn function.

onLogIn: function() {
            console.log("Login Successfull");
            this.loginStatus="Log Out"
        }

So what I am doing is changing text inside paper button from Log In to Log out. I have a property login status.

loginStatus:{
      type : String,
      value: "Log In",
      notify: true,
      reflectToAttribute: true
      }

When I try to change text in onLogIn method using this.loginStatus="Log Out". It says Uncaught TypeError: Cannot set property 'loginStatus' of undefined. So basically I saw this in my other codes too. I am not able to access ids of elements inside function inside a function. Same is the matter here I am not able to change value of property in function inside a function. How do I recover from this problem.

<paper-button raised class="custom indigo" id="logIn">[[loginStatus]]</paper-button>

Answer 1

The error message indicates that this is undefined . In your case, you should bind this when specifying the callback:

Digits.logIn().done(this.onLogIn.bind(this)).fail(this.onFail.bind(this));