How do I get the client's recaptcha g-recaptcha-response validation option after the user confirms that they are not a robot?

I am trying to implement google recaptcha on a form. The form issues an HTTP request to the server where it submits the data as a JSON object.

I added Google reCAPTCHA just before the form submit button with the following div tag:

     <div class="g-recaptcha" data-sitekey="{SITE_KEY}"></div>

      

        
        
        
      

    

Also I added the required JavaScript file to the header:

 <script src='https://www.google.com/recaptcha/api.js'></script>

      

        
        
        
      

    

Now the submit button issues a JavaScript function request like this: hence I am using Angular JS

  $scope.issueVideoUploadRequest = function () {

    var requestVideoUploadParameters = {
        videoSource: $scope.videoSource,
        title: $scope.title,
        description: $scope.description,
        videoLanguage: $scope.language,
        tagsList: $scope.tagsList
    };
    $http({
        method: "POST",
        dataType: "json",
        data: requestVideoUploadParameters,
        url: 'http://localhost:8080/OampSeniorProjectV2/rs/content/requestUploadForm'
    }).success(function (response, status, headers) {
        $scope.alertMessageVideoRequest = response;
        alert(response);
    }).error(function (response, status, headers, config) {
        $scope.reloadPage();
    });
};

      

        
        
        
      

    

The form is submitted to REST services.

The question is, where can I find the g-recaptcha-response parameter to send it back to the server along with the JSON object form? As I need this response value to perform server side validation.

I followed the documentation posted here