MSBuild Script to Compress All JavaScript Files in a Project

I’ve got one project in my solution which has a lot of JavaScript files and they keep on coming. We’ve been using the YUI Compressor for quite a while and it’s proven an effective tool. After a lot of time of fiddling with the project’s MSBuild script, I came up with the following:

<Target Name="BeforeBuild">
Condition="(%(Content.Extension) == '.js') And (!(Exists('compressed\%(Content.RelativeDir)')))" /> <Exec
Command="java -jar yuicompressor-x.y.z.jar --type js -o compressed\%(Content.Identity) %(Content.Identity)"
Condition="%(Content.Extension) == '.js'" /> <CreateItem
Condition="%(Content.Extension) == '.js'" /> </Target>

The above takes all of the JavaScript files in your project, compresses them (in the same relative directories) into the compressed directory and then adds them to the project, in case it gets deployed anywhere.

Note that I’m using the Extension, Identity and RelativeDir well-known item metadata attributes in order to impose batching, since batches causes loops instead of the string concatenation that happens when you reference the items themselves.


2 thoughts on “MSBuild Script to Compress All JavaScript Files in a Project

  1. Nice! Another option can be to use the JSCompress task from the MSBuild Community Tasks project. Although it doesn’t work well with CSS files (in which spaces are significant).

  2. You should add the following inside the CreateItem element:

    This way the items you create are created as content items and are copied together with the result binaries when you build\publish the project.

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