index.js

'use strict'
const gutil = require('gulp-util')
const through = require('through2')
const fs = require('fs')

module.exports = function (options) {
  options = options || {};
  let importStack = {}
  const importJS = (path) => {
    if (!path) {
      return ''
    }

    const fileReg = /@import\s["'](.*\.js)["']/gi

    if (!fs.existsSync(path)) {
      throw new Error('file ' + path + ' no exist')
    }

    let content = fs.readFileSync(path, {
        encoding: 'utf8'
    })

    importStack[path] = path

    content = content.replace(fileReg, (match, fileName) => {
      let importPath = path.replace(/[^\/]*\.js$/, fileName)

      if (importPath in importStack) {
        return ''
      }

      !options.hideConsole && console.log('import "' + fileName + '" --> "' + path + '"')
      let importContent = importJS(importPath) || ''

      return importContent
    })


    return content
  }

	return through.obj(function (file, enc, cb) {
		if (file.isNull()) {
			cb(null, file)
			return
		}

		if (file.isStream()) {
			cb(new gutil.PluginError('gulp-js-import', 'Streaming not supported'))
			return
		}

    let content
    try { 
      content = importJS(file.path)
    } catch(e) {
      cb(new gutil.PluginError('gulp-js-import', e.message))
      return
    }

		file.contents = new Buffer(content)
		file.path = gutil.replaceExtension(file.path, '.js')
		!options.hideConsole && console.log('ImportJS finished.')
		cb(null, file)
	})
}