Use es6 on visual tests

[GeoSot]

Merge after #36914

[julien-deramond]

Of course not mandatory for this PR: I just tried quickly but what would you think about adding some automation here with eslint-plugin-html?

Configuration would look like something like this:

diff --git a/.eslintignore b/.eslintignore
index a18b03a5d..04bae1541 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -3,4 +3,6 @@
 **/vendor/
 /_site/
 /js/coverage/
+/js/tests/integration/
 /site/static/sw.js
+/site/layouts/
diff --git a/js/tests/unit/.eslintrc.json b/js/tests/unit/.eslintrc.json
index 6362a1acf..6508fc062 100644
--- a/js/tests/unit/.eslintrc.json
+++ b/js/tests/unit/.eslintrc.json
@@ -1,4 +1,7 @@
 {
+  "plugins": [
+    "html"
+  ],
   "extends": [
     "../../../.eslintrc.json"
   ],
diff --git a/package.json b/package.json
index 50d4b35db..4db97cff1 100644
--- a/package.json
+++ b/package.json
@@ -63,7 +63,7 @@
     "js-compile-standalone-esm": "rollup --environment ESM:true,BUNDLE:false --config build/rollup.config.js --sourcemap",
     "js-compile-bundle": "rollup --environment BUNDLE:true --config build/rollup.config.js --sourcemap",
     "js-compile-plugins": "node build/build-plugins.js",
-    "js-lint": "eslint --cache --cache-location .cache/.eslintcache --report-unused-disable-directives .",
+    "js-lint": "eslint --cache --cache-location .cache/.eslintcache --report-unused-disable-directives --ext .html,.js .",
     "js-minify": "npm-run-all --aggregate-output --parallel js-minify-*",
     "js-minify-standalone": "terser --compress passes=2 --mangle --comments \"/^!/\" --source-map \"content=dist/js/bootstrap.js.map,includeSources,url=bootstrap.min.js.map\" --output dist/js/bootstrap.min.js dist/js/bootstrap.js",
     "js-minify-standalone-esm": "terser --compress passes=2 --mangle --comments \"/^!/\" --source-map \"content=dist/js/bootstrap.esm.js.map,includeSources,url=bootstrap.esm.min.js.map\" --output dist/js/bootstrap.esm.min.js dist/js/bootstrap.esm.js",
@@ -118,6 +118,7 @@
     "cross-env": "^7.0.3",
     "eslint": "^8.23.1",
     "eslint-config-xo": "^0.42.0",
+    "eslint-plugin-html": "^7.1.0",
     "eslint-plugin-import": "^2.26.0",
     "eslint-plugin-markdown": "^3.0.0",
     "eslint-plugin-unicorn": "^42.0.0",

And a new js/tests/visual/.eslintrc.json:

{
  "plugins": [
    "html"
  ],
  "extends": "../../../.eslintrc.json",
  "parserOptions": {
    "sourceType": "module"
  },
  "settings": {
    "html/html-extensions": [".html"]
  }
}

[GeoSot]

Of course not mandatory for this PR: I just tried quickly but what would you think about adding some automation here with eslint-plugin-html?

Linting is always a nice idea. Would you mind addressing it on a different PR?

[GeoSot]

Just for information, here is the report done by eslint-plugin-html without fine tuning it by removing useless rules. Maybe there are some things to you'd like to integrate right now in the modifications 🤷

Probably it will need an eslintrc.json override like bootstrap\site\.eslintrc.json

We can fix any issues there 😉

Thank you for your help @julien-deramond