AngularJS expressions are written inside double braces: {{ expression }}.
Expressions are used to bind application data to html. Expressions behaves in same way as ng-bind directives. AngularJS application expressions are pure javascript expressions and outputs the data where they are used. Here is the example for to get roll number from an object.,
<!DOCTYPE html>
<html>
<script src=js/angular.js”></script>
<body>
<div ng-app=””>
<p>Roll No: {{student.rollno}}</p>
</div>
</body>
</html>
Result : Roll No: 1024