Add a GitHub Action Workflow to run eslint. Install 10up-toolkit and …

…use it to run eslint, adding proper configurations. Also set things up to run stylelint, though we don't use that currently in an Action Workflow

.editorconfig

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+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = tab
+
+[{*.json,*.yml,.babelrc,.bowerrc,.browserslistrc,.postcssrc}]
+indent_style = space
+indent_size = 2
+
+[*.txt,wp-config-sample.php]
+end_of_line = crlf

.eslintignore

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+js/i18n
+js/datepicker.js
+js/scrollTo.js
+tests

.eslintrc.js

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+module.exports = {
+	extends: ['@10up/eslint-config/wordpress'],
+};

.github/workflows/eslint.yml

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+name: JS Linting
+
+on:
+  push:
+    branches:
+      - develop
+      - main
+    paths:
+      - '**.js'
+  pull_request:
+    branches:
+      - develop
+    paths:
+      - '**.js'
+
+jobs:
+  eslint:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+
+    - name: Setup node and npm cache
+      uses: actions/setup-node@v4
+      with:
+        node-version-file: .nvmrc
+        cache: npm
+
+    - name: Install Node dependencies
+      run: npm ci --omit=optional
+
+    - name: Get updated JS files
+      id: changed-files
+      uses: tj-actions/changed-files@v44
+      with:
+        files: |
+          **/*.js
+
+    - name: Run JS linting
+      if: ${{ steps.changed-files.outputs.any_changed == 'true' }}
+      run: ./node_modules/.bin/10up-toolkit lint-js ${{ steps.changed-files.outputs.all_changed_files }}

.nvmrc

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+v20