engine-munger

A replacement Express view class that provides asynchronous resolution, allows engines to use the lookup method to locate partials, and extends the lookup method to be configurable based on i18n locale and a template specialization rule map.

This is a backport of work for Express 5

Lead Maintainer: Aria Stewart

What does i18n mean?

i18n means "internationalization". Given a locale property in the render options, engine-munger will look for content in a locale-specific directory (or in a fallback locale if that is not a match) for templates and partials. This is particularly useful with template engines that pre-localize their compiled forms, such as with localizr and dustjs-linkedin together.

What does specialization mean?

Ability to switch a specific template with another based on a rule set specified in the app config. The actual rule parsing is done using the module karka.

All engine-munger does is includes a specialization map with the list of key value pairs using the karka module.

{
    specialization : {
        'jekyll': [
            {
                is: 'hyde',
                when: {
                    'whoAmI': 'badGuy'
                }
            }
        ]
    }
}

The above will switch the template from jekyll to hyde if the render options contain "whoAmI": "badGuy". Rules can be as complex as you need for your application and are particularly good for running A/B tests.

Using engine-munger in an application

This example uses the adaro template engine, which wraps dust up as an express view engine, and uses engine-munger's more sophisticated lookup method to find partials, allowing them to be localized and specialized based on the render options.

var munger = require('engine-munger');
var adaro = require('adaro');
var app = require('express')();
 
var specialization = {
    'jekyll': [
        {
            is: 'hyde',
            when: {
                'whoAmI': 'badGuy'
            }
        }
    ]
};
app.set("view", munger({
    "dust": {
        specialization: specialization
    },
    "js": {
        specialization: specialization,
        i18n: {
            fallback: 'en-US',
            contentPath: 'locales'
        }
    }
});
 
var engineConfig = {}; // Configuration for your view engine
 
app.engine('dust', adaro.dust(engineConfig));
app.engine('js', adaro.js(engineConfig));

Running Tests:

npm test

To run coverage:

npm run cover