Move index.js to web_src and use webpack to pack them (#8598)

* Move index.js to web_src and use webpack

* Fix initHeatMap

* update eslint and move webpack to devDependencies

* update index.js

* add eslint env node

Author: lunny

.eslintrc

@@ -10,6 +10,7 @@ env:
   browser: true
   jquery: true
   es6: true
+  node: true
 
 globals:
   Clipboard: false

Makefile

@@ -434,7 +434,8 @@ npm-update: npm-check
 
 .PHONY: js
 js: npm
-	npx eslint public/js
+	npx eslint web_src/js webpack.config.js
+	npx webpack
 
 .PHONY: css
 css: npm

package-lock.json

@@ -12,7 +12,9 @@
     "postcss-cli": "6.1.3",
     "stylelint": "10.1.0",
     "stylelint-config-standard": "18.3.0",
-    "updates": "8.5.3"
+    "updates": "8.5.3",
+    "webpack": "4.41.2",
+    "webpack-cli": "3.3.10"
   },
   "browserslist": [
     "> 1%",