AngularJS Example:

by gangadharjannu

HTML

<link rel="stylesheet" href="http://twitter.github.com/bootstrap/assets/css/bootstrap.css">
<div ng-app ng-controller="TodoCtrl">
  <button ng-click="addScript()">Add jQuery dynamically
  </button>
  </button>
</div>

JavaScript

function TodoCtrl($scope) {
  $scope.addScript = function() {
    if (!document.querySelectorAll("script[src*='com/jquery-1.9.1.min.js']").length) {
      var js = document.createElement("script");
      js.id = 'dynamicScript';
      js.type = "text/javascript";
      js.src = 'https://code.jquery.com/jquery-1.9.1.min.js';
      document.body.appendChild(js);
    }
  }
}