Dojo: The Definitive Guide

Core IO

This section explains the dojo.io facilities that are provided by Core. Injecting dynamic SCRIPT tags to retrieve padded JSON and hacking IFRAME s into a viable transport layer are the central topics of discussion.

Using JSONP with Dojo

You know enough about Dojo by this point that you won't be surprised to know that it streamlines the work involved in implementing JSONP. To accomplish the same functionality as what was described in the primer, you could use dojo.io.script.get, which takes most of the same parameters as the various XHR methods. Notable caveats are that handleAs really isn't applicable for JSONP, and callbackParamName is needed so that Dojo can set up and manage a callback function to be executed on your behalf.

Here's an example of how it's done:

//dojo.io.script is not part of Base, so remember to require it into the page
dojo.require("dojo.io.script");

dojo.io.script.get({
  callbackParamName : "c", //provided by the jsonp service
  url: "http://example.com?id=23",
  load : function(response, ioArgs) {
    console.log(response);
    return response;
  },
  error : function(response, ioArgs) {
    console.log(response);
    return response;
  }
});

To clarify, the callbackParamName specifies the name of the query string parameter that is established by example.com. It is not the name of a function you've defined to act as a callback yourself. Behind the scenes, Dojo manages the callback by creating a temporary function and channeling the response into the load function, following the same ...