index.js

var es = require('event-stream');
var gutil = require('gulp-util');
var Buffer = require('buffer').Buffer;
var jstransform = require('jstransform');

module.exports = function(opt){
  function modifyFile(file){
    if (file.isNull()){
      return this.emit('data', file); // pass along
    } 
    if (file.isStream()){
      return this.emit('error', new Error("gulp-jstransfrom: Streaming not supported"));
    } 
    // Influenced by https://github.com/stoyan/etc/master/es6r/es6r.js
    var str = file.contents.toString('utf8');
    var visitors = [];
    [
      require('jstransform/visitors/es6-arrow-function-visitors'),
      require('jstransform/visitors/es6-class-visitors'),
      require('jstransform/visitors/es6-object-concise-method-visitors'),
      require('jstransform/visitors/es6-object-short-notation-visitors'),
      require('jstransform/visitors/es6-rest-param-visitors'),
      require('jstransform/visitors/es6-template-visitors')
    ].forEach(function(visitor) {
      visitors = visitors.concat(visitor.visitorList);
    });
   
    var converted = jstransform.transform(visitors, str);
    file.contents = new Buffer(converted.code);
    this.emit('data', file);
  }

  return es.through(modifyFile);
};