.njk File — Nunjucks Template

Nunjucks is a rich and powerful JavaScript template engine inspired by Jinja2 (Python), developed by Mozilla. NJK files use a syntax nearly identical to Jinja2/Twig with {{ }} for expressions, {% %} for statements, and {# #} for comments. Nunjucks provides template inheritance, includes, macros, filters, custom tags, asynchronous control, and auto-escaping. The engine is particularly popular in the JavaScript ecosystem for static site generation — Eleventy (11ty), one of the fastest-growing static site generators, supports Nunjucks as a first-class template language. Nunjucks runs both in Node.js (for server-side rendering and static site generation) and in the browser (for client-side templating). The template inheritance system allows defining base layouts with blocks that child templates override, enabling DRY template hierarchies. Nunjucks supports asynchronous operations in templates, useful for data fetching during rendering. Custom filters and extensions can add project-specific functionality. The engine precompiles templates for production performance and provides helpful error messages during development. Nunjucks' Jinja2-compatible syntax makes it familiar to developers from the Python ecosystem.