How to Load External Data Into a Fiddle

If you attempt to load data from an external domain into a Fiddle you’re likely going to receive an XMLHttpRequest error that looks something like “Origin is not allowed by Access-Control-Allow-Origin”. You can use JSFiddle’s echo requests if you just want to simulate returning data, but sometimes you want to demonstrate an actual retrieval.

Legitimate security concerns regarding cross-site HTTP requests are the reason why you can’t simply read in any old file. However, using appropriate page headers makes accessing files from other domains possible. So, if we can set page headers in a file that returns our data, it should be accessible, right? Right!

This can’t be done using a JSON file, but it can be done in a PHP file that is setup to output JSON. The PHP code would look something like this:

// Allow access from anywhere. Can be domains or * (any)

// Allow these methods of data retrieval
header('Access-Control-Allow-Methods: POST, GET, OPTIONS');

// Allow these header types
header('Access-Control-Allow-Headers: Origin, X-Requested-With, Content-Type, Accept');

// Create our data object in that crazy unique PHP way
$arr = array(array("id" => 1, "character" => "Minstrel", "line" => "And Saint Attila raised the hand grenade up on high, saying, 'O Lord, bless this thy hand grenade, that with it thou mayst blow thine enemies to tiny bits, in thy mercy.' And the Lord did grin."));

// Return as JSON
echo json_encode($arr);

Note that you don’t have to use PHP. You can use just about any server side scripting language; ASP, .NET, ColdFusion, Ruby, etc., as long as you set the headers properly.

Check out an example:
[iajsfiddle fiddle=”bNyqY” height=”200px” width=”100%” show=”result,html,js,css” skin=”default”]

Plunk, Pen or Fiddle?

I’ve experienced some frustration recently with all of the big three code sandboxes: JSFiddle, Plunker, and CodePen. I’d originally picked Plunker because it provides the ability to create separate datasource files that can be used in my Plunks. This is extremely useful, especially when demonstrating how to load an external data source.

About a week ago while viewing my own post in Appliness digital magazine (shameless plug) I noticed that I couldn’t access the source code in the embedded iFrame. I wasn’t sure if this was an oddity with Appliness so I made a mental note to check it out.

The very next day I received a comment from a visitor stating that they were having the same problem when viewing the site on their phone. Obviously, I had a problem. I want my code to be viewable on as many devices as possible so I started looking into alternatives.



For looks, you can’t beat CodePen. It’s definitely the Ferrari of the bunch. Its sleek black skin and optional upgrades made me want to take it for a spin. The CodePen window is made up of four frames, HTML, CSS, JS, and the Output. Each code frame has its own set of additional features/libraries accessible via a small gear icon in the upper right corner.

CodePen’s additional features are very slick and useful. The HTML frame allows you to utilize three useful templating tools, Haml, Markdown and Slim, at the click of a button. CSS provides easy access to Less and Sass as well as some other oft-used CSS functionality, like reset. And JS frame applies clickable access to Coffeescript and Modernize, as well as allowing you to add any external library of your choosing. It also provides a useful link to where you can find a CDN reference to just about any library yo can think of.


CodePen felt great, looked great, and provided optional upgrades. Unfortunately, once you take it out of the garage and park it in your driveway, i.e., embed it on your site, it doesn’t necessarily run great.


As a matter of fact, my Angular code which works when viewed on CodePen, did not work at all on my site. The Ferrari of sandboxes actually seems more like a Fiero with a Ferrari kit.



JSFiddle seems to be the most widely-used sandbox. It’s the most utilitarian of the three…the minivan, if you will. Its looks are very basic, and while it claims the ability to apply different skins when embedded, the only skins available are “light” (light gray and white) and “presentation” (light gray and white with a gigantic font). You would think if there was a “light” there would also be a “dark”, right? Nope. This minivan only comes in gray.

Like CodePen, JSFiddle displays HTML, JS, CSS, and output frames. It provides access to a slew of libraries via a too-huge dropdown list. It also provides a second dropdown with esoteric options like “no wrap – in head”, which actually turns out to be quite important. The rest of the options are hidden in a vertical accordion.


The most important difference between CodePen and JSFiddle, however, is only apparent when it’s embedded. JSFiddle works and CodePen doesn’t.



Plunkr is a little different than the others. It’s no Ferrari, but it’s no minivan either. I guess it’s a Buick. It’s looks are more modern than JSFiddles, but its options are almost non-existent. The window only has two frames: code and output. You create your own files rather than using dedicated HTML, JS, and CSS frames. While this means that you can’t look at all of your code at once, it actually lends to its flexibility.

With Plunkr you can create multiple files in the same project. This means you can test more abstractly, and easily swap functionality in and out. Your HTML head is in your code window making it easy to see what’s getting loaded. Being able to create your own files also means being able to create external datasources, which is fantastic for playing with dataloading functionality.


The biggest problem with Plunker is the one I mentioned earlier. When it’s embedded, you can’t view the source files on mobile devices.

So, what do you drive, a Fiero/Ferrari, a minivan, or a Buick? Or something entirely different?