Filters

Fil­ters let you post­pro­cess your out­put. Think of it like in­sta­gram for web­sites, but use­ful. You can con­fig­ure per file ex­ten­sion a se­ries of python func­tions or shell com­mand­s, which will be ap­plied in place to the out­put file.

For ex­am­ple, sup­pose you want to ap­ply yui-­com­pres­sor to your CSS and JS files:

FILTERS = {
    ".css": [filters.yui_compressor],
    ".js": [filters.yui_compressor],
}

There, filters.yui_compressor is a simple wrapper around the command so that it applies in-place to the output files.

If you use strings there (untest­ed), they are tak­en as com­mand­s. The "%s" will be re­placed by the file­name, the usu­al crazy shell quot­ing rules ap­ply:

FILTERS = {
    ".jpg": ["jpegoptim '%s'"],
    ".png": ["pngoptim '%s'"],
}

Keep in mind that the fil­ters mod­i­fy the out­put of Niko­la, not the in­put, so your im­ages, CSS, and JS files will not be touched in any way. And of course chang­ing the fil­ters ap­plied to a file will force a re­build, so you can ex­per­i­ment freely.

Bundles

Hav­ing many sep­a­rate CSS or JS files is usu­al­ly a nono for per­for­mance rea­sons be­cause each one may in­volve a sep­a­rate HTTP trans­ac­tion. The so­lu­tion is to "bundle" those files in a sin­gle, larg­er file.

The rea­son not to do that is that usu­al­ly it means hav­ing a huge, un­com­fort­able thing to han­dle. So Niko­la tries to give you the best of both world­s, by let­ting you have sep­a­rate files, and bundling them (or not) on build.

There is a new option, USE_BUNDLES that defaults to False, and there are some changes in the theme templates so that it uses the bundled version when needed.

This was on­ly pos­si­ble thanks to We­bas­sets. How­ev­er, if you don't have We­bas­sets in­stalled, or you don't en­able USE_BUNDLES, this should cause no changes in the out­put.

Conclusion

These new fea­tures will al­low Niko­la users to im­prove their site's per­for­mance with min­i­mal tweak­ing, which is al­ways a good thing.