From 037139f614f685280d15789e27aa388b20fd655d Mon Sep 17 00:00:00 2001
From: "Nicholas C. Zakas" <nicholas@nczconsulting.com>
Date: Tue, 28 Jun 2016 11:03:34 -0700
Subject: [PATCH] Chore: First ES6 refactoring (refs #6407)

First steps in taking advantage of ES6 features:

1. Remove es6-map dependency (no longer needed)
2. Use babelify to create browser bundle
3. Refactor a couple files into ES6 classes
---
 .eslintrc.yml                             |  4 ++++
 Makefile.js                               |  6 +++---
 lib/config/environments.js                | 20 ++++++++++----------
 lib/rules/no-unmodified-loop-condition.js |  3 +--
 lib/rules/prefer-const.js                 |  1 -
 package.json                              |  4 +++-
 6 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/.eslintrc.yml b/.eslintrc.yml
index 84f6d55539c..0486c031a8f 100644
--- a/.eslintrc.yml
+++ b/.eslintrc.yml
@@ -2,6 +2,10 @@ root: true
 
 env:
     node: true
+    es6: true
+
+parserOptions:
+    ecmaVersion: 6
 
 extends:
     "./packages/eslint-config-eslint/default.yml"
diff --git a/Makefile.js b/Makefile.js
index 64082c5076f..bcb55628c7f 100644
--- a/Makefile.js
+++ b/Makefile.js
@@ -688,13 +688,13 @@ target.browserify = function() {
     generateRulesIndex(TEMP_DIR);
 
     // 5. browserify the temp directory
-    nodeCLI.exec("browserify", "-x espree", TEMP_DIR + "eslint.js", "-o", BUILD_DIR + "eslint.js", "-s eslint");
+    nodeCLI.exec("browserify", "-x espree", TEMP_DIR + "eslint.js", "-o", BUILD_DIR + "eslint.js", "-s eslint", "-t [ babelify --presets [ es2015 ] ]");
 
     // 6. Browserify espree
     nodeCLI.exec("browserify", "-r espree", "-o", TEMP_DIR + "espree.js");
 
-    // 7. Concatenate the two files together
-    cat(TEMP_DIR + "espree.js", BUILD_DIR + "eslint.js").to(BUILD_DIR + "eslint.js");
+    // 7. Concatenate Babel polyfill, Espree, and ESLint files together
+    cat("./node_modules/babel-polyfill/dist/polyfill.js", TEMP_DIR + "espree.js", BUILD_DIR + "eslint.js").to(BUILD_DIR + "eslint.js");
 
     // 8. remove temp directory
     rm("-r", TEMP_DIR);
diff --git a/lib/config/environments.js b/lib/config/environments.js
index 8daef864e31..d1ef5703f03 100644
--- a/lib/config/environments.js
+++ b/lib/config/environments.js
@@ -14,7 +14,7 @@ var envs = require("../../conf/environments");
 // Private
 //------------------------------------------------------------------------------
 
-var environments = Object.create(null);
+var environments = new Map();
 
 /**
  * Loads the default environments.
@@ -23,7 +23,7 @@ var environments = Object.create(null);
  */
 function load() {
     Object.keys(envs).forEach(function(envName) {
-        environments[envName] = envs[envName];
+        environments.set(envName, envs[envName]);
     });
 }
 
@@ -36,15 +36,15 @@ load();
 
 module.exports = {
 
-    load: load,
+    load,
 
     /**
      * Gets the environment with the given name.
      * @param {string} name The name of the environment to retrieve.
      * @returns {Object?} The environment object or null if not found.
      */
-    get: function(name) {
-        return environments[name] || null;
+    get(name) {
+        return environments.get(name) || null;
     },
 
     /**
@@ -53,8 +53,8 @@ module.exports = {
      * @param {Object} env The environment settings.
      * @returns {void}
      */
-    define: function(name, env) {
-        environments[name] = env;
+    define(name, env) {
+        environments.set(name, env);
     },
 
     /**
@@ -63,7 +63,7 @@ module.exports = {
      * @param {string} pluginName The name of the plugin.
      * @returns {void}
      */
-    importPlugin: function(plugin, pluginName) {
+    importPlugin(plugin, pluginName) {
         if (plugin.environments) {
             Object.keys(plugin.environments).forEach(function(envName) {
                 this.define(pluginName + "/" + envName, plugin.environments[envName]);
@@ -75,8 +75,8 @@ module.exports = {
      * Resets all environments. Only use for tests!
      * @returns {void}
      */
-    testReset: function() {
-        environments = Object.create(null);
+    testReset() {
+        environments = new Map();
         load();
     }
 };
diff --git a/lib/rules/no-unmodified-loop-condition.js b/lib/rules/no-unmodified-loop-condition.js
index ed49b5996ef..efb65434836 100644
--- a/lib/rules/no-unmodified-loop-condition.js
+++ b/lib/rules/no-unmodified-loop-condition.js
@@ -9,8 +9,7 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-var Map = require("es6-map"),
-    Traverser = require("../util/traverser"),
+var Traverser = require("../util/traverser"),
     astUtils = require("../ast-utils");
 
 //------------------------------------------------------------------------------
diff --git a/lib/rules/prefer-const.js b/lib/rules/prefer-const.js
index 7b8ac425193..121021118c4 100644
--- a/lib/rules/prefer-const.js
+++ b/lib/rules/prefer-const.js
@@ -9,7 +9,6 @@
 // Requirements
 //------------------------------------------------------------------------------
 
-var Map = require("es6-map");
 var lodash = require("lodash");
 
 //------------------------------------------------------------------------------
diff --git a/package.json b/package.json
index abe440dcd62..c7f6fc5ae13 100644
--- a/package.json
+++ b/package.json
@@ -40,7 +40,6 @@
     "concat-stream": "^1.4.6",
     "debug": "^2.1.1",
     "doctrine": "^1.2.2",
-    "es6-map": "^0.1.3",
     "escope": "^3.6.0",
     "espree": "^3.1.6",
     "estraverse": "^4.2.0",
@@ -71,6 +70,9 @@
     "user-home": "^2.0.0"
   },
   "devDependencies": {
+    "babel-polyfill": "^6.9.1",
+    "babel-preset-es2015": "^6.9.0",
+    "babelify": "^7.3.0",
     "beefy": "^2.0.0",
     "brfs": "0.0.9",
     "browserify": "^12.0.1",