Add Babel to build process (close snowplow#665)

Author: mhadam

.babelrc

@@ -0,0 +1,10 @@
+{
+  "presets": [["@babel/preset-env", {
+    "targets": {
+      "chrome": 32,
+      "ie": 9,
+      "firefox": 27,
+      "safari": 8
+    }
+  }]]
+}

Gruntfile.js

@@ -89,7 +89,23 @@ module.exports = function(grunt) {
         files: {
           'tests/pages/helpers.js': ['tests/scripts/helpers.js'],
           'tests/pages/detectors.js': ['tests/scripts/detectors.js'],
-          'tests/pages/snowplow.js': ['src/js/init.js']
+          'tests/pages/bundle.js': ['src/js/init.js']
+        }
+      }
+    },
+
+    babel: {
+      options: {
+        presets: ['@babel/preset-env']
+      },
+      dist: {
+        files: {
+          'dist/bundle-postbabel.js': 'dist/bundle.js'
+        }
+      },
+      test: {
+        files: {
+          'tests/pages/snowplow.js': 'tests/pages/bundle.js'
         }
       }
     },
@@ -101,7 +117,7 @@ module.exports = function(grunt) {
           'banner': '<%= banner %>',
           'process': true
         },
-        src: ['dist/bundle.js'],
+        src: ['dist/bundle-postbabel.js'],
         dest: 'dist/snowplow.js'
       },
       tag: {
@@ -175,6 +191,7 @@ module.exports = function(grunt) {
   grunt.loadNpmTasks('grunt-browserify');
   grunt.loadNpmTasks('intern');
   grunt.loadNpmTasks('grunt-contrib-uglify');
+  grunt.loadNpmTasks('grunt-babel');
 
   grunt.registerTask('upload_setup', 'Read aws.json and configure upload tasks', function() {
     var aws = grunt.file.readJSON('aws.json');
@@ -242,11 +259,11 @@ module.exports = function(grunt) {
     });
   });
 
-  grunt.registerTask('default', 'Build Browserify, add banner, and minify', ['browserify:main', 'concat:deploy', 'uglify:deploy']);
-  grunt.registerTask('publish', 'Upload to S3 and invalidate Cloudfront (full semantic version only)', ['upload_setup', 'browserify:main', 'concat:deploy', 'uglify:deploy', 's3:not_pinned', 'cloudfront:not_pinned']);
-  grunt.registerTask('publish-pinned', 'Upload to S3 and invalidate Cloudfront (full semantic version and semantic major version)', ['upload_setup', 'browserify:main', 'concat:deploy', 'uglify:deploy', 's3', 'cloudfront']);
-  grunt.registerTask('quick', 'Build snowplow.js, skipping building and minifying', ['browserify:main', 'concat:deploy']);
-  grunt.registerTask('test', 'Intern tests', ['browserify:test', 'intern']);
-  grunt.registerTask('travis', 'Intern tests for Travis CI',  ['concat:test', 'browserify:test', 'intern']);
+  grunt.registerTask('default', 'Build Browserify, add banner, and minify', ['browserify:main', 'babel:dist', 'concat:deploy', 'uglify:deploy']);
+  grunt.registerTask('publish', 'Upload to S3 and invalidate Cloudfront (full semantic version only)', ['upload_setup', 'browserify:main', 'babel:dist', 'concat:deploy', 'uglify:deploy', 's3:not_pinned', 'cloudfront:not_pinned']);
+  grunt.registerTask('publish-pinned', 'Upload to S3 and invalidate Cloudfront (full semantic version and semantic major version)', ['upload_setup', 'browserify:main', 'babel:dist', 'concat:deploy', 'uglify:deploy', 's3', 'cloudfront']);
+  grunt.registerTask('quick', 'Build snowplow.js, skipping building and minifying', ['browserify:main', 'babel:dist', 'concat:deploy']);
+  grunt.registerTask('test', 'Intern tests', ['browserify:test', 'babel:test', 'intern']);
+  grunt.registerTask('travis', 'Intern tests for Travis CI',  ['concat:test', 'browserify:test', 'babel:test', 'intern']);
   grunt.registerTask('tags', 'Minifiy the Snowplow invocation tag', ['uglify:tag', 'concat:tag']);
 };

package.json

@@ -10,10 +10,14 @@
     "sha1": "git://github.com/pvorb/node-sha1.git#910081c83f3661507d9d89e66e3f38d8b59d5559"
   },
   "devDependencies": {
+    "@babel/core": "^7.1.2",
+    "@babel/preset-env": "^7.1.0",
     "JSON": "1.0.0",
+    "babel-cli": "^6.26.0",
     "grunt": "0.4.5",
     "grunt-aws": "0.6.2",
-    "grunt-browserify": "5.0.0",
+    "grunt-babel": "^8.0.0",
+    "grunt-browserify": "^5.0.0",
     "grunt-contrib-concat": "0.5.1",
     "lodash": "^4.17.11",
     "grunt-contrib-uglify": "^4.0.0",