The filters provided by the Jade template engine enable us to indicate the method that should be used when processing a specific block in a template. This is usually used for blocks of content that are written in a format other than the Jade language itself. As an example, the coffee and markdown filters provided by the Jade library provide the rendering of CoffeeScript code into JavaScript and Markdown content into HTML.
In this recipe, we'll make use of the contrib-jade (0.12.0) plugin in conjunction with its filters option to make a custom filter called link available to us in our templates. This filter will use a simplistic algorithm to find URLs and surround them with an anchor tag, turning them into links.
In this example, we'll work with the basic project structure we created in the Rendering Jade templates recipe of this chapter. Be sure to refer to it if you are not yet familiar with its contents.