Sharing nunjucks filters across node and browser

Question

I am trying to find a way to get my filter works on both side.

Here is the code I have on node :

var env = nunjucks.configure(__dirname + '/../templates', {
    express: app
});

env.addFilter('date', function(str){
    return 'ok';
});

And on browser side :

var env = new nunjucks.Environment();
env.addFilter('date', function(str){
    return 'ok';
});

I would like to have my filter in a place where it will be available in these two different environments but I don't find a solution to do so.

On client side I am using nunjucks-slim version. My templates are precompiled using gulp.

Thanks for your help !

Answer 1

You could put your filters in a separate file/module, where you pass env in as an argument.

eg.

/**
* @param env The nunjucks environment
*/
function(env){
    env.addFilter('fancy', function(input){
        return 'fancy ' + input
    });

    env.addFilter(...);

    return env;
}

You could then use a UMD wrapper (https://github.com/umdjs/umd) to make it compatible with both browser and server. The finished wrapper might look something like this:

// custom_filters.js
(function (root, factory) {
    if (typeof define === 'function' && define.amd) {
        // AMD. Register as an anonymous module.
        define([], factory);
    } else if (typeof exports === 'object') {
        // Node. Does not work with strict CommonJS, but
        // only CommonJS-like environments that support module.exports,
        // like Node.
        module.exports = factory();
    } else {
        // Browser globals (root is window)
        root.custom_filters = factory();
    }
}(this, function () {

    // Return a value to define the module export.
    return function(env){
        env.addFilter('fancy', function(input){
            return 'fancy ' + input
        });

        return env;
    };
}));

Then use it like this:

Node:

var env = nunjucks.configure(__dirname + '/../templates', {
    express: app
});
require('./path/to/custom_filters')(env);

Browser (Globals):

var env = new nunjucks.Environment();
window.custom_filters(env);

Browser (AMD):

define(
    ['nunjucks', 'path/to/custom_filters'],
    function(nunjucks, custom_filters){
        var env = new nunjucks.Environment();
        return custom_filters(env);
    }
);