index.js

const staticModule = require('static-module')
const from2 = require('from2-string')
const through = require('through2')
const assert = require('assert')
const d = require('defined')
const bl = require('bl')
const fs = require('fs')

module.exports = cssExtract

// Extract CSS from a browserify bundle
// obj -> null
function cssExtract (bundle, opts) {
 opts = opts || {}

 var outFile = opts.out || opts.o || 'bundle.css'
 var sourceMap = d(opts.sourceMap, bundle && bundle._options && bundle._options.debug, false)

 assert.strictEqual(typeof bundle, 'object', 'bundle should be an object')
 assert.strictEqual(typeof opts, 'object', 'opts should be an object')

 // every time .bundle is called, attach hook
 bundle.on('reset', addHooks)
 addHooks()

 function addHooks () {
 const extractStream = through.obj(write, flush)
 const writeStream = (typeof outFile === 'function')
 ? outFile()
 : bl(writeComplete)

 // run before the "label" step in browserify pipeline
 bundle.pipeline.get('label').unshift(extractStream)

 function write (chunk, enc, cb) {
 // Performance boost: don't do ast parsing unless we know it's needed
 if (!/(insert-css|sheetify\/insert)/.test(chunk.source)) {
 return cb(null, chunk)
 }

 var source = from2(chunk.source)
 var sm = staticModule({
 'insert-css': function (src) {
 writeStream.write(String(src) + '\n')
 return from2('null')
 },
 'sheetify/insert': function (src) {
 writeStream.write(String(src) + '\n')
 return from2('null')
 }
 }, { sourceMap: sourceMap })

 source.pipe(sm).pipe(bl(complete))

 function complete (err, source) {
 if (err) return extractStream.emit('error', err)
 chunk.source = String(source)
 cb(null, chunk)
 }
 }

 // close stream and signal end
 function flush (cb) {
 writeStream.end()
 cb()
 }

 function writeComplete (err, buffer) {
 if (err) return extractStream.emit('error', err)
 fs.writeFileSync(outFile, buffer)
 }
 }
}