🎨(frontend) Minor refactoring

- improve condition statements
- add "no-var" rule in eslint
- remove some unnecessary variables

Signed-off-by: Zorin95670 <moittie.vincent@gmail.com>

src/frontend/servers/y-provider/.eslintrc.cjs

@@ -13,5 +13,5 @@ module.exports = {
   rules: {
     '@next/next/no-html-link-for-pages': 'off',
   },
-  ignorePatterns: ['node_modules', '.eslintrc.js'],
+  ignorePatterns: ['node_modules'],
 };

src/frontend/servers/y-provider/jest.config.js

@@ -1,4 +1,4 @@
-var config = {
+const config = {
   rootDir: './__tests__',
   testEnvironment: 'node',
   transform: {