Visual Studio 2013 RTM was shipped with a feature – /// <autosync enabled=”true” /> for _references.js file.
In order to work with the feature, you need to create a new MVP project and open scripts/_references.js file. You will view a screenshot as shown below
You can drag and drop bootstrap.js file to the Scripts folder to make a copy. You will be able to see that all the missing “.js” files and the newly added “.js” files are automatically referenced in the _references.js file.
Mads Kristensen has published a detailed blog post which examines the complete story behind _references.js.