npm install -g wintersmith-nunjucks
From the nunjucks documentation at http://jlongster.github.io/nunjucks/templating.html#filters:
Filters are essentially functions that can be applied to variables. They are called with a pipe operator (|) and can take arguments.
For more information on how to write customer Filters, take a look at the API documentation page at: http://jlongster.github.io/nunjucks/api#custom-filters
To use customer filters with wintersmith, put the filter in its own file stored in a filters directory. The filename has to be the name of the filter + '.js'.
so if your filter is in './filters/myfirstfilter.js' add a nunjucks section like this to your config.json:
"nunjucks":"filterdir": "filters""filters": "myfirstfilter"
It will be available in your templates at 'myfirstfilter'
this specific filter would then be available as
date in your templates.
As of nunjucks 2 autoescaping was turned on by default. This plugin reverts that since autoescaping is not usually wanted when used in a static site generator. If you want to change behaviour for some reason you can control it with the autoescape option in your config.json.