JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.0/angular.min.js"></script>
<div ng-app ng-controller="myCtrl">
    <input type="file" ng-model="image" onchange="angular.element(this).scope().uploadImage(this.files)" /> 
  
</div>

JavaScript

function myCtrl($scope) {
    $scope.uploadImage = function (files) {       
       var ext = files[0].name.match(/\.(.+)$/)[1];
        if(angular.lowercase(ext) ==='jpg' || angular.lowercase(ext) ==='jpeg' || angular.lowercase(ext) ==='png'){
            alert("Valid File Format");
        }  
        else{
            alert("Invalid File Format");
        }
    }
}