Javascript Sandbox for ASP.NET MVC 3

October 21st, 2011 by Gareth / Comments

I’ve started reading more about Javascript this year. My home project is coming up to the point where I’m making some important client side decisions and I want to make sure I’m making the best choices.

As anyone who has looked beyond the surface will tell you, Javascript is deceptively complex and capable. I have four books helping me out at the moment :

I recommend all four. I started reading Javascript Web Applications by Alex MacCaw because I wanted to understand how Javascript frameworks like KnockoutJS, BackboneJS and JavascriptMVC are constructed rather than just use them and this book is exactly for that purpose. For me it quickly proved to be a bit too “in at the deep end” so I’ve switched to Javascript Enlightenment by Cody Lindley to get a solid and deep understanding of Javascript.

All these books have code examples and I learn best by following, experimenting and pushing the samples with questions that pop up. So how does an ASP.NET MVC developer play around with Javacsript?

  • You could have a folder full of HTML files and chuck your javascript in there, and run them individually
  • You could use JS Fiddle
  • You could spend three hours creating a modest little sandbox framework built as an ASP.NET MVC app

I did the last one. At one point I abandoned it and switched to JS Fiddle, but then I went back to it. I prefer messing about in my own environment sometimes.

I’ll call your individual Javascript fiddles a sandcastle because I’m looking left and right and can’t see anyone telling me not to (although I am alone in my upstairs office). A Javascript sandcastle is created as a view like this :

  1. Description : Optional description of what your javascript is testing
  2. Javascript_Setup : Stick your setup code in here
  3. Javascript_Test : The code that runs against the Javascript_Setup code

Then edit the Home/Index view to add a link to your new test. As you can see from the screenshot in the link I’ve added the html helper @Html.SandboxLink(sandboxViewName,description) to simplify generating links to your Javascript tests. I want to automate this at some point in the future so you only need to create the views.

The advantage you will notice at this point is that you get Intellisense in your sandcastle because it’s all in an ASP.NET MVC view in Visual Studio. The other advantage comes from how the _SandboxLayout.cshtml  page presents the results. Here’s what you see when you’ve run a test :

Your sandcastle is presented nicely and formatted using the terrific Syntax Highlighter by Alex Gorbatchev. There is a generous 500ms pause while I wait for the formatting to complete then I run your test code. In your JavaScript you can call the helper log() function which outputs to the Log area at the bottom thus completing your test and showing you what happened. Logging helps to see the flow of the code which isn’t always obvious with Javascript, look at a slightly more complex example to see what I mean.

When I’ve grokked the good parts of Javscript the next step on my client side journey is Javascript unit testing. When I mention “test” in this blog post I’m not talking about unit testing an application’s code, I’m talking about isolated tests that’ll help you figure out some code – a tiny bit like how we use LinqPad (but that’s in a different league of course).

You can download this project from my Javascript Sandbox For ASP.NET MVC 3 Github page (I’m really enjoying using it to learn Javascript) or you could use JSFiddle and wonder with bemusement why I spent 3 hours putting this project together, 2 hours writing this blog post and 15 minutes messing about with Git when I could have finished the book by now and be back working on my home project.

My home project is such a long way off because every little step of the way I’m going down all these rabbit holes and discovering that rabbit droppings taste good.

ASP.NET MVC, Javascript, jQuery

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