How to use JSON as config file with Javascript

something like

var cfg = {};
$.ajax({
  url: myUrl,
  async: false,
  success: function(data) {
    cfg = JSON.parse(data);
  }
});

If you don't want to use an asynchronous call you can always assign a variable to the config object and put the file in the src of a script tag

var appConfig={
    'Lang' : 'EN',
    'URL' : '/over/dose/app'
}

.

<script src="/path/to/config.js"></script>
<script> alert(appConfig.URL);</script>

Advantage is immediate loading. Possible disadvantage is it isn't a json file any more, it is regular javascript file in case you are writing to it from server code.

Of course this also creates a global variable.