bundler.js

/* global module */

/**
 * Based on https://github.com/substack/node-browserify/issues/1044#issuecomment-139384663
 */
(function (module) {
    module.exports = bundleEntry;

    var through2 = require('through2'),
        browserify = require('browserify'),
        watchify = require('watchify');

    var cachedBundles = {};

    function bundleEntry(onUpdate, shouldWatch) {
        shouldWatch = shouldWatch || false;

        var transformation = through2.obj(function (file, enc, next) {
            var filename = file.path;
            var config = {
                entries: [filename],
                transform: []
            };

            function onBundleCB(err, res) {
                if (err) {
                    return next(err);
                }

                file.contents = res;
                next(null, file);
            }

            // Watchify configs
            if (shouldWatch) {
                if (cachedBundles[filename]) {
                    // Already created a watched bundle, just rebundle
                    return cachedBundles[filename].bundle(onBundleCB);
                } else {
                    config.cache = {};
                    config.packageCache = {};
                    config.debug = false;
                }
            }

            var b = browserify(config);

            if (shouldWatch) {
                b = watchify(b);
                cachedBundles[filename] = b;
                b.on('update', function () {
                    console.log(filename + " changed. Rebundling...");
                    onUpdate(filename);
                });
            }

            b
                .on('error', handleError) // No idea if this is needed (just calls this.end)
                .bundle(onBundleCB);
        });

        return transformation;
    }

    function handleError() {
        console.log('Bundle error');
        console.log(arguments);
        this.emit('end'); // Keep gulp from hanging on this task
    }

})(module);