Separate variable assignment and usage into two expressions
<script src="angular.min.js"></script>
<div ng-app>
<div>
Result
{{ x + y }}
</div>
<div>
Assignment:
{{ x = 23; y= 19 }}
</div>
<div>
Result
{{ x + y }}
</div>
</div>
Result 42
Assignment: 19
Result 42