Response headers in test server in JavaScript

Our server is able to send different HTTP headers. For this, the second parameter of a callback is used:

server.jsexport default {
  '/handler/': function(data, resp) {
    // resp parameter for headers
  }
}

Using the setHeader method, we can set any header. For example, let's set the MIME type to JSON:

server.jsexport default {
  '/handler/': function(data, resp) {
    resp.setHeader('Content-Type', 'application/json');
    return '[1,2,3]';
  }
}