I'm trying to disable enable a button based on an input type value. Here is the Angular JS html code

<div ng-app>

    <form name=myForm ng-controller=ctrl>

        <input type=text ng-model=name ng-required=true />

        <span>{{name}}</span>

        <input type=submit value=Submit ng-disabled=myForm.name.$pristine />

    </form>

</div>

And the controller code:

function ctrl($scope){

    $scope.name = hello;

}

But the button is not getting disabled no matter what.

Here is the DEMO

NOTE: I want the button to be disabled only when text box doesn't have any value and vice versa