I have a registration form with the textbox username. I want to do is when the entered username is exist, there is a label beside the textbox displaying "username exist" without clicking the submit button. What I've done so far is : <http://jsfiddle.net/DharkRoses/s2qe3omh/2/> Any help would be much appreciated. 

sample of my code: 

```
<div ng-app="myApp" ng-controller="check">
<div class = "container">
    <h3>Registration form</h3>    
      <form name = "myForm">
             <label>Username:</label>
                <input type = "text" id = "user" ng-model="username"></input>
             <div class="msg-block" ng-show="myForm.$error"> <span class="msg-error" ng-show="myForm.user.$error.user">User exists.</span> 
     </form>
    <button ng-click = "userExists(username)">Submit</button>

```