json_dependency.js

function JsonFile(path) {
  this.path = path;
}

JsonFile.prototype = new loadrunner.Dependency;

JsonFile.prototype.start = function() {
  var me = this;

  $.get(this.path, function(data) {
    me.complete(data);
  }, 'json');
};

using.matchers['\\.json$'] = function(path) {
  return new JsonFile(path);
};