index.js

var gutil = require('gulp-util')
var merge = require('deepmerge')
var through = require('through2')
var browserify = require('browserify')
var watchify = require('watchify')
var prettyTime = require('pretty-hrtime')

var cache = {}

var log = {
    start: function (file, status, opt) {
        gutil.log(
            status,
            gutil.colors.magenta(file.relative),
            opt.watch !== false ? '(watch mode)' : ''
        )
    },
    end: function (file, status, opt, startAt) {
        gutil.log(
            status,
            gutil.colors.magenta(file.relative),
            'finished after',
            prettyTime(process.hrtime(startAt))
        )
    }
}

module.exports = function(taskCallback) {

    function getBundle(file, opt) {
        var path = file.path
        if (cache[path]) {
            return cache[path]
        }
        if (opt.watch !== false) {
            opt = merge(opt, watchify.args)
        }
        var bundle = browserify(opt)
        if (opt.watch !== false) {
            bundle = watchify(bundle, opt) // modifies bundle to emit update events
            cache[path] = bundle
            bundle.on('update', function() {
                bundle.updateStatus = 'updated'
                taskCallback(plugin)
            })
        }
        bundle.updateStatus = 'first'
        if (opt.setup) {
            opt.setup(bundle)
        }

        return bundle
    }
    function plugin(opt) {
        return through.obj(function(file, enc, callback){
            if (file.isNull()) {
                this.push(file) // Do nothing if no contents
                return callback()
            }
            if (file.isStream()) {
                return callback(new Error('gulp-watchify ignores streams'))
            }
            var options = merge(opt, { entries:'./'+file.relative, basedir:file.base })
            var bundle = getBundle(file, options)
            var startAt = process.hrtime()
            var status;
            if (bundle.updateStatus) {
                status = bundle.updateStatus === 'first' ? 'Bundling' : 'Rebundling'
                log.start(file, status, opt)
                file = file.clone()
                delete bundle.updateStatus
                file.contents = bundle.bundle()
                // Wait until done or else streamify(uglify()) fails due to buffering
                file.contents.on('error', callback)
                file.contents.on('end', function () {
                  log.end(file, status, opt, startAt)
                  callback()
                })
                this.push(file)
            } else {
                callback()
            }
        })
    }
    // Return wrapped Task
    return function() {
        return taskCallback(plugin)
    }
}