simple-nunjucks-loader

Nunjucks templates loader for Webpack

This Webpack loader compiles Nunjucks templates. html-webpack-plugin compatible.

Install

npm install --save-dev simple-nunjucks-loader

If you don't use dynamic assets in your code, then you could save a bit on optional glob dependency:

npm install --no-optional --save-dev simple-nunjucks-loader

Usage

This loader will precompile Nunjucks templates. It also includes Nunjunks (slim) runtime for browser.

Add loader to your webpack config as follows:

webpack.config.js

module.exports = {
    module: {
        rules: [
            {
                test: /\.njk$/,
                use: [
                    {
                        loader: 'simple-nunjucks-loader',
                        options: {}
                    }
                ]
            }
        ]
    }
};

template.njk

<p>Hello, {{ username }}!</p>

index.js

import template from './template.njk'

document.body.innerHTML = template({
  username: 'Mike'
})

Bundling of index.js above will render paragraph with text "Hello, Mike!" to the page.

More examples on loader site.

How it works

By default Nunjunks bundle all precompiled templates to window.nunjucksPrecompiled, then loads them via custom loader from this global object. If precompiled template reference some other template file, it is loaded from disk (in NodeJS environment), or fetched via XMLHttpRequest from internet and precompile downloaded template in runtime.

Both are not webpack-way for projects bundling.

This loader got template source, parse it with Nunjucks parser, to get AST of template. This AST is iterated to get info on imported templates, used filters and extensions.

Next step is precompile template, to make it faster. Loader injects own wrapper to avoid default behaviour with creating global window.nunjucksPrecompiled.

One final step is gather all parts together. Loader is inserts imports of templates, filters and extensions that somehow noted in template, this will make Webpack to rebuild template only when one of essential part is changed.

Then loader expose module that will create separate environment with only required filters and extensions. This module is what you invoke to get your template rendered.

Assets support

Loader add own {% static %} tag, for loading assets, and track their change.

Signature is same to static tag from Django.

template.njk

<img alt="" src="{% static 'image.jpg' %}" />

See more examples of setup and using assets in loader.

Asynchronous support

When loader found async tags or async filters or extensions in the template, it calls render with callback under the hood, and returns Promise, instead of render result.

Because of asynchronous nature of Webpack assets loading, all assets, that loaded via {% static %} tag, make template to return Promise too.

Options

Loader supports limited number of Nunjuncks options. It's doesn't support watch (we use webpack own dependencies watch), noCache, web settings and express.

All other options get passed to Nunjunks Environment during files loading.

Name	Type	Default	Description
jinjaCompat	{Boolean}	false	Install Jinja syntax support in bundle
searchPaths	{String} or {Array.<string>}	.	One or more paths to resolve templates paths
assetsPaths	{String} or {Array.<string>}	.	Paths to resolve static assets. Works like STATICFILES_DIRS.
globals	Object.<string, string>	{}	Map global function to corresponding module
extensions	Object.<string, string>	{}	Map extension to corresponding module
filters	Object.<string, string>	{}	Map filters to corresponding module
autoescape	{Boolean}	true	See Nunjuncks options for description of options below
throwOnUndefined	{Boolean}	false
trimBlocks	{Boolean}	false
lstripBlocks	{Boolean}	false
tags	{Object.<string, string>}	Default Jinja tags config	Override tags syntax

tags default to:

{
    blockStart: '{%',
    blockEnd: '%}',
    variableStart: '{{',
    variableEnd: '}}',
    commentStart: '{#',
    commentEnd: '#}'
}

jinjaCompat

Installs Jinja syntax. This option install it for whole bundle.

searchPaths

Loader is searching for full template relative to given string(s) from searchPath option (or project root, if no paths given).

Path to file couldn't be outside of folders above.

webpack.config.js

module.exports = {
    module: {
        rules: [
            {
                test: /\.njk$/,
                use: [{
                    loader: 'simple-nunjucks-loader',
                    options: {
                        searchPaths: [
                            'django_app_a/templates',
                            'django_app_b/templates'
                        ]
                    }
                }]
            }
        ]
    }
};

assetsPaths

List of paths where loader should search for assets.

module.exports = {
    module: {
        rules: [
            {
                test: /\.njk$/,
                use: [{
                    loader: 'simple-nunjucks-loader',
                    options: {
                        assetsPaths: [
                            'django_app_a/static',
                            'django_app_b/static'
                        ]
                    }
                }]
            }
        ]
    }
};

globals

Set global function and import path, that should return function to use. It the same function that env.addGlobal using.

webpack.config.js

module.exports = {
    module: {
        rules: [
            {
                test: /\.njk$/,
                use: [{
                    loader: 'simple-nunjucks-loader',
                    options: {
                        globals: {
                            _: 'lodash',
                            globalFn: path.join(__dirname, 'global-fn.js')
                        }
                    }
                }]
            }
        ]
    }
};

global-fn.js

module.exports = function globalFn(foo, bar) {
    return `Do anything with ${foo} and ${bar}`;
};

extensions

Set map of extensions that would be imported before each template render. Extension should return instance, that would be added via env.addExtension.

webpack.config.js

module.exports = {
    module: {
        rules: [
            {
                test: /\.njk$/,
                use: [{
                    loader: 'simple-nunjucks-loader',
                    options: {
                        extensions: {
                            CustomExtension: path.join(__dirname, 'extension.js')
                        }
                    }
                }]
            }
        ]
    }
};

:boom: Using ES modules syntax for extensions is not yet possible

extension.js

// You should use slim bundle to make it work in browser
const nunjucks = require('nunjucks/browser/nunjucks-slim');

// See example in docs
// https://mozilla.github.io/nunjucks/api.html#custom-tags
class CustomExtension {}

module.exports = new CustomExtension();

Loader trying to guess which extensions are really used, and keep only required imports.

filters

Map of filters, that would be imported before each template render. Filter should return instance, that would be added via env.addFilter.

webpack.config.js

module.exports = {
    module: {
        rules: [
            {
                test: /\.njk$/,
                use: [{
                    loader: 'simple-nunjucks-loader',
                    options: {
                        filters: {
                            filter: path.join(__dirname, 'filter.js')
                        }
                    }
                }]
            }
        ]
    }
};

:boom: Using ES modules syntax for filters is not yet possible

filter.js

module.exports = function filter(val, param) {
    return `${val + param}`;
};

template.njk

{{ foo_var | filter(3) }}

Nunjucks is not aware that filter is asynchronous when parse template to AST. Because of that, you should mark filter as async. To do that, filter module should export async flag:

async-filter.js

function asyncFilter(val, param, callback) {
    setTimeout(function() {
        callback(null, val + param);
    }, 1000);
}

asyncFilter.async = true;

module.exports = asyncFilter;