O'Reilly

JSONP with jQuery, MooTools, and Dojo

By on  

JSONP MooTools jQuery

We all know that the big limitation of AJAX is that cross-domain requests aren't allowed.  We also know, however, that we skirt around that rule a bit by using JSONP.  JSONP is the process of SCRIPT tag injection, referencing a cross-domain URL and providing a callback function (on your page) that the provider will call so that you can handle the result.  Let's take a look at how JSONP is handled with jQuery, MooTools, and the Dojo Toolkit.  For our examples, we'll pull tweets from Twitter with the term "Arsenal" in them.

jQuery JSONP

jQuery uses the same method for JSONP as it does for regular JSON -- the jQuery.getJSON method:

jQuery.getJSON("http://search.twitter.com/search.json?callback=?",{
	q: "Arsenal"
},function(tweets) {
	// Handle response here
	console.info("Twitter returned: ",tweets);
});

As long as a callback parameter is provided to the getJSON method, jQuery will consider the request JSONP.

MooTools JSONP

MooTools requires the Request.JSONP Class available in MooTools More.  Armed with Request.JSONP, fetching JSON from another domain is a piece of cake:

new Request.JSONP({
	url: "http://search.twitter.com/search.json",
	data: {
		q: "Arsenal"
	},
	onComplete: function(tweets) {
		// Log the result to console for inspection
		console.info("Twitter returned: ",tweets);
	}
}).send();

Request.JSONP is a super compact class too!

Dojo JSONP

JSONP with the Dojo Toolkit requires the dojo.io.script resource and its get method:

// dojo.io.script is an external dependency, so it must be required
dojo.require("dojo.io.script");

// When the resource is ready
dojo.ready(function() {
	
	// Use the get method
	dojo.io.script.get({
		// The URL to get JSON from Twitter
		url: "http://search.twitter.com/search.json",
		// The callback paramater
		callbackParamName: "callback", // Twitter requires "callback"
		// The content to send
		content: {
			q: "Arsenal"
		},
		// The success callback
		load: function(tweetsJson) {  // Twitter sent us information!
			// Log the result to console for inspection
			console.info("Twitter returned: ",tweetsJson);
		}
	});
});

Retrieving JSON with Dojo is usually done with the dojo.xhrGet method, but JSONP request this special method.  The arguments for dojo.io.script.get are the same as dojo.xhrGet with the exception of the callback parameter.

JSONP is a hugely effective, reliable, and easy to implement.  JSONP strategies also allow developers to avoid cumbersome server-side proxy writing to retrieve data.  Each of the JavaScript libraries above have battle-tested methods for retrieving JSON data across domains -- it's up to you to implement them to suit your needs!

O'Reilly Velocity Conference
Save 20% with discount code AFF20

Recent Features

  • How to Create a Twitter Card

    One of my favorite social APIs was the Open Graph API adopted by Facebook.  Adding just a few META tags to each page allowed links to my article to be styled and presented the way I wanted them to, giving me a bit of control...

  • Vibration API

    Many of the new APIs provided to us by browser vendors are more targeted toward the mobile user than the desktop user.  One of those simple APIs the Vibration API.  The Vibration API allows developers to direct the device, using JavaScript, to vibrate in...

Incredible Demos

  • Using MooTools For Opacity

    Although it's possible to achieve opacity using CSS, the hacks involved aren't pretty. If you're using the MooTools JavaScript library, opacity is as easy as using an element's "set" method. The following MooTools snippet takes every image with the "opacity" class and sets...

  • Making the Firefox Logo from HTML

    When each new t-shirt means staving off laundry for yet another day, swag quickly becomes the most coveted perk at any tech company. Mozilla WebDev had pretty much everything going for it: brilliant people, interesting problems, awesome office. Everything except a t-shirt. That had to change. The basic...

Discussion

  1. Cool! Thanks for sharing! :)

  2. In my plugd project I have a script.js plugin, which provides functionality similar to $.getJSON without requiring io.script (though doesn’t use the same Promises all other Dojo IO things use)

  3. For those interested, Pete’s plugd can be found at: https://github.com/phiggins42/plugd

  4. the only way i could make it work was this

    $.ajax({
      url: url,
      dataType: 'jsonp',
      data: parameters,
      mimeType:"application/json",
      complete:function(jqXHR, textStatus){
          console.log("Ajax completado. ");
      },
      success: function(data, textStatus, jqXHR){
          if(console !=undefined)
            {
                console.log(textStatus);
                console.info(jqXHR);
            }
            twitterCallback2(data);
      },
      error:function(jqXHR, textStatus, errorThrown){
          console.log("Error: "+textStatus+errorThrown);
      }
    });
    
  5. wooop. Thanks David you animal

  6. Vic

    now we still need a clever way to make POST requests using cross domain ajax calls, I think there are some initiatives around called jsonp tunnels

  7. Lolki

    Euh, what is Arsenal ?

    :) just kidding ! ;)

  8. Thomas

    It is worth noting that these examples only work as the jsonp files you are requesting are generated dynamically, that is why you need the callback=?.

    If you are trying to load in static json files, say from a CDN you will need to wrap you json data in something like this myFunction({ [ "data" : "value"] });

    Then in your js file you need your ajax call, and a function that has the same name as your wrapper in the json file.

     $.ajax({url: "http://otherdomain.com/json.json",dataType: "jsonp",cache: false,jsonp:'onJsonPLoad',jsonpcallbackString: "myFunction"}) ;
    
    // callback function
    myFunction(data)
    {
    // do stuff with the json data
    console.log(data)
    }
    

    Of course, if you have access to PHP on the server that is dishing up your JSON files you can have the jsonp file like this

    And David’s methods will work a treat.

    • Thomas

      Forgot to wrap the php bit

    • Thomas


      echo $_GET['callback'] .'({["data" : "value" ]})';

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!

Recently on David Walsh Blog

  • Open Files from Command Line on OS X

    I'm as much of a fan of application UIs as anyone else but I'm finding myself working more and more from the command line lately.  Much of that is becoming obsessed with media manipulation but I'm forcing myself to use less UIs so that I...

  • Get Stock Quotes From Command Line

    When I conned my way into my first professional programming gig, I didn't really think much about money -- just that I was getting my foot in the door.  But as my career has gone on, I've been more aware of money, investing, and retirement.  I've recently...

  • Geolocation API

    One interesting aspect of web development is geolocation; where is your user viewing your website from? You can base your language locale on that data or show certain products in your store based on the user's location. Let's examine how you can...

  • Create an Image Preview from a Video

    Visuals are everything when it comes to media.  When I'm trying to decide whether to watch a video on Netflix, it would be awesome to see a trailer of some kind, but alas that isn't available.  When I'm looking to download a video on my computer,...

  • New:  Webdesigner News!

    A new and exciting website has recently been launched for web designers and developers. You likely spend hours every morning browsing through hundreds of posts on your RSS feeds, hoping to stumble across relevant stories. Webdesigner News was built to provide web designers and developers with...