Besides cURL, the JSON server may also be accessed via javascript.

JSON module comes with the json_server.js file that provides a method to access the server via Javascript. The JSON server module provides the json_load() function that simplifies the inclusion of the json_server.js file at page render time.

Drupal.service('service.name', 
  {api_key: "123461823762348756293", sessid: "sdfjahsldjfhlaksuertybsi", extra_parameter: "asdfasdf", other_parameter: ["nodes", "are", "good"]}, 
  function(status, data) {
    if(status == false) {
      alert("FATAL ERROR!!!!!");
    }
    else {
      alert(data);
    }
  }
);

Drupal.service takes three parameters: service name, parameters, and callback function.
The callback function accepts two parameters returned by the service - the success/failure of the request and data.
Data is usually an object, and if the success if false, it contains a useful message.

This can be very useful for debugging services or even using JSON server for ajax callbacks.

Consider an the following example that would call the node.load service using the JSON server. Upon clicking a link, a call is made to the service and upon success the contents of the node are inserted into the page.

$('a.classname').bind('click', function() {
  Drupal.service('node.load',
    {nid: 2, fields: ["nid", "title", "body"]},
    function(status, data) {
      if(status == false) {
        alert("Fatal error: could not load content");
      }
      else {
        $('#content_area').html("<h1><a href=\""+ data.nid + "\">"+ data.title +"</a></h1><br /><p>"+ data.body +"</p>");
      }
    }
  );
}