Browserify - ParseError: 'import' and 'export' may appear only with 'sourceType: module

Question

In my gulpfile I have

var gulp = require(\'gulp\');
var browserSync = require(\'browser-sync\').create();
var sass = require(\'gulp-sass\');
var babel = requ         


        

Answer 1

Simply switching to webpack instead of browserify fixed the issue for me.

var webpack = require('webpack-stream')

gulp.task('default', function () {
  return gulp.src('src/source.js')
    .pipe(webpack({
      output: {
        filename: 'app.js'
      }
    }))
    .pipe(gulp.dest('dist/app.js'))
})

Answer 2

Browserify in Gulp

For those who work with gulp and want to transpile ES6 to ES5 with browserify, you might stumble upon gulp-browserify plug-in. Warning as it is from version 0.5.1 gulp-browserify is no longer suported!!!. Consequences, of this action and transpiling with gulp-browserify will result with source code that might produce errors such as the one in question or similar to these: Uncaught ReferenceError: require is not defined or Uncaught SyntaxError: Unexpected identifier next to your import statements e.g. import * from './modules/bar.es6.js';

Solution

Althoutg gulp-browserify recomends to "checkout the recipes by gulp team for reference on using browserify with gulp". I found this advice to no avail. As it is now (2st July 2019) solution that worked for me was to replace gulp-browserify with gulp-bro@1.0.3 plug-in. This successfully, transpired ES6 to ES5 (as it is now) - It might change in future since support for JavaSript libraries decays with time of it appearance.

Assumption: To reproduce this solution you should have installed docker. Beside that you should be familiar with babel and babelify.

Source Code

This solution was successfully reproduced in docker environment, run node:11.7.0-alpine image.

Project Structure

/src                          <- directory
/src/app/foo.es6.js
/src/app/modules/bar.es6.js
/src/app/dist                 <- directory
/src/app/dist/app.es5.js
/src/gulpfile.js
/src/.babelrc
/src/package.json
/src/node_modules             <- directory

Step 1: Run docker image

$ docker run --rm -it --name bro_demo node:11.7.0-alpine ash

Step 2: Create directories and source files

$ mkdir -p /src/dist
$ mkdir -p /src/app/modules/
$ touch /src/app/foo.es6.js
$ touch /src/app/modules/bar.es6.js
$ touch /src/gulpfile.js
$ touch /src/.babelrc
$ touch /src/package.json
$ cd /src/

$ apk add vim

.babelrc

{
  "presets": ["@babel/preset-env"]
}

package.json

{
  "name": "src",
  "version": "1.0.0",
  "description": "",
  "main": "",
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@babel/core": "^7.4.5",
    "@babel/preset-env": "^7.4.5",
    "babelify": "^10.0.0",
    "gulp": "^4.0.2",
    "gulp-bro": "^1.0.3",
    "gulp-rename": "^1.2.2"
  }
}

bar.es6.js

"use strict"

class Bar {
  constructor(grammar) {
    console.log('Bar time!');
  }
}

export default Bar;

foo.es6.js

"use strict"

import Bar from './modules/bar.es6.js';

class Foo {
  constructor(grammar) {
    console.log('Foo time!');
  }
}

var foo = new Foo()
var bar = new Bar()

gulpfile.js

const bro = require('gulp-bro');
const gulp = require('gulp');
const rename = require('gulp-rename');
const babelify = require('babelify');

function transpileResources(callback) {
  gulp.src(['./app/foo.es6.js'])
    .pipe(bro({transform: [babelify.configure({ presets: ['@babel/preset-env'] })] }))
    .pipe(rename('app.es5.js'))
    .pipe(gulp.dest('./dist/'));

  callback();
}

exports.transpile = transpileResources;

Step 3 - Transpile ES6 to ES5

$ npm install
$ npm install -g gulp@4.0.2

$ gulp transpile
[09:30:30] Using gulpfile /src/gulpfile.js
[09:30:30] Starting 'transpile'...
[09:30:30] Finished 'transpile' after 9.33 ms

$ node dist/app.es5.js
Foo time!
Bar time!

Source code after transpilation app.es5.js

(function(){function r(e,n,t){function o(i,f){if(!n[i]){if(!e[i]){var c="function"==typeof require&&require;if(!f&&c)return c(i,!0);if(u)return u(i,!0);var a=new Error("Cannot find module '"+i+"'");throw a.code="MODULE_NOT_FOUND",a}var p=n[i]={exports:{}};e[i][0].call(p.exports,function(r){var n=e[i][1][r];return o(n||r)},p,p.exports,r,e,n,t)}return n[i].exports}for(var u="function"==typeof require&&require,i=0;i<t.length;i++)o(t[i]);return o}return r})()({1:[function(require,module,exports){
"use strict";

var _barEs = _interopRequireDefault(require("./modules/bar.es6.js"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { "default": obj }; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Foo = function Foo(grammar) {
  _classCallCheck(this, Foo);

  console.log('Foo time!');
};

var foo = new Foo();
var bar = new _barEs["default"]();

},{"./modules/bar.es6.js":2}],2:[function(require,module,exports){
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports["default"] = void 0;

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var Bar = function Bar(grammar) {
  _classCallCheck(this, Bar);

  console.log('Bar time!');
};

var _default = Bar;
exports["default"] = _default;

},{}]},{},[1]);

Answer 3

In your configuration, you pipe js/main.js to Babel, so that's the only file that will be transpiled. When Browserify requires app.js, it will seen ES6 content and will effect the error you are seeing.

You could use Babelify to solve the problem. It's a Browserify transform that will transpile the source that Browserify receives.

To install it, run this command:

npm install babelify --save-dev

And to configure it, change your task to:

gulp.task('js', function () {
    gulp.src('js/main.js')
        .pipe(browserify({ transform: ['babelify'] }))
        .on('error', errorAlert)
        .pipe(rename('./dist/js/bundle.js'))
        //.pipe(uglify())
        .pipe(gulp.dest('./'))
        .pipe(notify({ title: "Success", message: "Well Done!", sound: "Glass" }));
})