You are developing a client application (AngularJS) and you need to receive the data from a REST API service.
Often you don’t have the access to the remote service or it doesn’t have the required data for your tests (dinamically generated data).

A direct access to a test .json file is not possible from the client because of security restrictions of the browser (the browser should not be able to play with the filesystem).

Solution – Concept

A client app can request (GET) a pre-defined page to a local server and receive the JSON file for the test.
The server can be implemented in Node.js and it serves static files content as response to http requests.


Solution – Implementation

The code and the installation procedure are here:

The structure of the code is very simple:

Here an example of response:


Solution – Details

The file server.js create a new http server and waits for http requests.
It instantiates a loaderModule that contain the class that will retrieve the JSON data.

// import the function from the module
    var loaderModule = require('./ResponseLoader.js');
    // create an instance of the prototype
    var loader = new loaderModule("loader");

    function requestService(request, response){
        // url == filename without extension 
        var url = request.url;
        // home page called
        if (url=="/"){
            url = "/index";
        // call the method that load the static page 
        // prepare the http response
        response.statusCode = 200;
        response.setHeader('Content-Type', 'application/json');
        // add the JSON content

The second important Javascript file is the function that receives the request to load a file and retrieves the content:

function ResponseLoader (name){

    // the content of the file is stored in this variable
    var json;

    // method that load the file on the base of the URL
    ResponseLoader.prototype.load = function(url){
        console.log("requested file: " + url);
        // url: hello -> file: [current directory]/json/hello.json
        fs.readFile( __dirname + '/json' +url+'.json', function (err, data) {
            if (err) {
                throw err;
            // the content of the file is assigned to the variable
            json = data;

            console.log(name + " : " +data.toString());

    // give me the json content
    ResponseLoader.prototype.getJson = function (){
        console.log(name + " : return json");

        return json;

The features are very basic but they can be easily extended. The code is modularized using the ‚module‘ feature of node.js.
If you come from Java / .NET : the import of modules is not standard in JavaScript until ECMAScript 6.