Eli Weinstock-Herman

Using T4 templates for Centralized Javascript

Original post posted on December 02, 2011 at LessThanDot.com

In my previous post I mentioned that I was looking for an answer to the age-old question of how to manage common CSS and JavaScript across multiple projects (specifically ASP.Net projects). Using T4 templates, I was able to not only create a common location for CSS files, but to take it a step farther and use Less in ordr to simplify that common CSS even further.

But we left JavaScript out of the equation.

T4'ing the JavaScript

As a reminder, I am looking for a clean way to store shared JavaScript and CSS in a single place so I share it amongst several web projects and also make changes to the files on the fly and see them in the browser without a costly solution rebuild.

On the JavaScript side of things I decided to write my own little T4 template. The goal was to be able to pick up all of the *.js files in a central location, merge them, and save them out as a common file that I could then include in my local projects.

My solution layout is similar to the one in the prior post:

Code: text
/SolutionName/Common/NN-*.js files

I prefix my common javascript files with a 2-digit number so I can include them in a planned order every time.


Code: c#
<#@ template language="C#" hostspecific="True" #>
<#@ import namespace="System" #>
<#@ import namespace="System.IO" #>
<#@ import namespace="Microsoft.VisualStudio.TextTemplating" #>
<#@ Output Extension=".js" #>
// Settings      
string _targetDirectory = @"\..\..\Common";
Directory.SetCurrentDirectory(Path.GetDirectoryName(Host.TemplateFile) + _targetDirectory);
var filespec = "*.js";
var files = Directory.GetFiles(".",filespec);
Converted at: <#= DateTime.Now.ToShortDateString() #> <#= DateTime.Now.ToShortTimeString() #>
File List (<#= files.Length #> Found):
<#= "\t" + String.Join("\n\t", files) #>
foreach(var jsFile in files)
    Write("/* ----------- " + jsFile + " ----------- */\n");
    using(StreamReader sr = File.OpenText(jsFile))
    Write("\n/* ----------- " + jsFile + " ----------- */\n\n");

Place this file in our project, update the _targetDirectory variable and we have a quick way to pull common javascript down to our projects.

The output file is a merged version of all of the *.js files found in the common folder. I also output comments around each file block to make it easy to track back to the original file, if needed.

The Price of Hack and Slash Code

I put this script together very quickly and, as such, it is missing some features I think would be nice additions. The ability to execute a minification run at the end would be nice, as would the MarkDirty feature that was in the T4CSS.tt code.

As with the previous post, the sample project is available, so you can look at (or download) a working example if you would like.

And that is that. Shortest Eli post ever? Maybe :)

Comments are available on the original post at lessthandot.com