diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 53803da..2bc22b2 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -5,36 +5,81 @@ on:
     branches: [ main ]
   pull_request:
     branches: [ main ]
+    workflow_dispatch: # Allow manual workflow execution
+
+# Allow only one running workflow per branch
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 
 jobs:
   test:
+    name: Test (Node.js ${{ matrix.node-version }})
     runs-on: ubuntu-latest
+    timeout-minutes: 10
 
     strategy:
+      fail-fast: false # Test all Node versions even if one fails
       matrix:
         node-version: [lts/*, current]
 
     steps:
     - name: Checkout
       uses: actions/checkout@v5
+      with:
+        # For better coverage reports
+        fetch-depth: 0
 
-    - name: Use Node.js ${{ matrix.node-version }}
+    - name: Setup Node.js ${{ matrix.node-version }}
       uses: actions/setup-node@v5
       with:
         node-version: ${{ matrix.node-version }}
+        cache: 'npm'
 
     - name: Install dependencies
-      run: npm ci
+      run: npm ci --prefer-offline --no-audit
 
     - name: Analyze JavaScript files
       run: npm run-script lint
 
     - name: Run test suite
-      run: |
-        npm test
-        npm run-script coverage
+      run: npm test
+
+    - name: Generate coverage report
+      run: npm run-script coverage
 
-    - name: Push coverage report
-      uses: coverallsapp/github-action@master
+    - name: Upload coverage report to Coveralls
+      if: matrix.node-version == 'lts/*' # Only upload once
+      uses: coverallsapp/github-action@v2
       with:
         github-token: ${{ secrets.GITHUB_TOKEN }}
+        path-to-lcov: ./coverage/lcov.info
+
+  jquery-compatibility:
+    name: jQuery Compatibility Tests
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    strategy:
+      fail-fast: false
+      matrix:
+        jquery-version: ['3.7.1', '4.0.0-rc.1']
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v5
+
+    - name: Setup Node.js
+      uses: actions/setup-node@v5
+      with:
+        node-version: 'lts/*'
+        cache: 'npm'
+
+    - name: Install dependencies
+      run: npm ci --prefer-offline --no-audit
+
+    - name: Install jQuery ${{ matrix.jquery-version }}
+      run: npm install jquery@${{ matrix.jquery-version }}
+
+    - name: Run test suite with jQuery ${{ matrix.jquery-version }}
+      run: npm test
diff --git a/README.md b/README.md
index 0344177..a61a9dd 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ The most common use case would be:
 ```html
 <p><a href="https://example.com/" title="example.com">Go to example site</a>
 
-<script src="http://code.jquery.com/jquery-3.6.0.slim.min.js"></script>
+<script src="http://code.jquery.com/jquery-4.0.0.slim.min.js"></script>
 <script src="jquery.externalize.js"></script>
 <script>
 $('a[href*="//"]').externalize();
@@ -63,7 +63,7 @@ Another use case: Opening PDF files in a new window.
 ```html
 <p><a href="/download/sample.pdf">Download PDF</a>
 
-<script src="http://code.jquery.com/jquery-3.6.0.slim.min.js"></script>
+<script src="http://code.jquery.com/jquery-4.0.0.slim.min.js"></script>
 <script src="jquery.externalize.js"></script>
 <script>
 $('a[href$=".pdf"]').externalize({
diff --git a/jquery.externalize.js b/jquery.externalize.js
index 03aff68..3a688ca 100644
--- a/jquery.externalize.js
+++ b/jquery.externalize.js
@@ -5,7 +5,7 @@
  *
  * @see https://github.com/mrcgrtz/jquery-externalize
  * @author Marc Görtz (https://marcgoertz.de/)
- * @copyright 2011-2017
+ * @copyright 2011-2025
  * @license MIT License
  * @example $('a[href*="//"], a[rel="external"]').externalize();
  * @param options Configuration object (see defaults in plugin function)
@@ -27,11 +27,12 @@ $.fn.externalize = function( options ) {
 
 		// save item and some useful information about it
 		var $this = $( this ),
-		isLink = $this.get( 0 ).nodeName === "A" || $this.get( 0 ).nodeName === "AREA",
+		nodeName = this.nodeName,
+		isLink = nodeName === "A" || nodeName === "AREA",
 		hasHref = $this.attr( "href" ),
 
 		// if any options were supplied, apply them to the configuration object
-		config = $.extend( defaults, options );
+		config = $.extend( {}, defaults, options );
 
 		// is this really a link with an "href" attribute?
 		if ( isLink && hasHref ) {
diff --git a/package-lock.json b/package-lock.json
index 1fa06fa..e5855ad 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -15,11 +15,11 @@
         "eslint-config-jquery": "^3.0.0",
         "eslint-formatter-pretty": "^7.0.0",
         "globals": "^16.0.0",
-        "jquery": "^3.7.1",
+        "jquery": "4.0.0-rc.1",
         "jsdom": "^27.0.0"
       },
       "peerDependencies": {
-        "jquery": "^1.7.0 || ^2 || ^3"
+        "jquery": "^1.7.0 || ^2 || ^3 || ^4"
       }
     },
     "node_modules/@aashutoshrathi/word-wrap": {
@@ -174,6 +174,7 @@
           "url": "https://opencollective.com/csstools"
         }
       ],
+      "peer": true,
       "engines": {
         "node": ">=18"
       },
@@ -218,6 +219,7 @@
           "url": "https://opencollective.com/csstools"
         }
       ],
+      "peer": true,
       "engines": {
         "node": ">=18"
       }
@@ -752,6 +754,7 @@
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.15.0.tgz",
       "integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
       "dev": true,
+      "peer": true,
       "bin": {
         "acorn": "bin/acorn"
       },
@@ -1563,6 +1566,7 @@
       "resolved": "https://registry.npmjs.org/eslint/-/eslint-9.36.0.tgz",
       "integrity": "sha512-hB4FIzXovouYzwzECDcUkJ4OcfOEkXTv2zRY6B9bkwjx/cprAq0uvm1nl7zvQ0/TsUk0zQiN4uPfJpB9m+rPMQ==",
       "dev": true,
+      "peer": true,
       "dependencies": {
         "@eslint-community/eslint-utils": "^4.8.0",
         "@eslint-community/regexpp": "^4.12.1",
@@ -2483,10 +2487,11 @@
       }
     },
     "node_modules/jquery": {
-      "version": "3.7.1",
-      "resolved": "https://registry.npmjs.org/jquery/-/jquery-3.7.1.tgz",
-      "integrity": "sha512-m4avr8yL8kmFN8psrbFFFmB/If14iN5o9nw/NgnnM+kybDJpRsAynV2BsfpTYrTRysYUdADVD7CkUUizgkpLfg==",
-      "dev": true
+      "version": "4.0.0-rc.1",
+      "resolved": "https://registry.npmjs.org/jquery/-/jquery-4.0.0-rc.1.tgz",
+      "integrity": "sha512-ima3YNbwR733XSQ/yFbO4Kjq7Z01feW8BmzZ4VjuuFvWVpGdjXSpmOJZRaehA4V60Aj97HsHNRnDM188c8pHHw==",
+      "dev": true,
+      "license": "MIT"
     },
     "node_modules/js-string-escape": {
       "version": "1.0.1",
@@ -2824,7 +2829,6 @@
           "url": "https://github.com/sponsors/ai"
         }
       ],
-      "peer": true,
       "bin": {
         "nanoid": "bin/nanoid.cjs"
       },
@@ -3071,8 +3075,7 @@
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
       "integrity": "sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==",
-      "dev": true,
-      "peer": true
+      "dev": true
     },
     "node_modules/picomatch": {
       "version": "4.0.2",
@@ -4138,6 +4141,7 @@
       "resolved": "https://registry.npmjs.org/@csstools/css-parser-algorithms/-/css-parser-algorithms-3.0.5.tgz",
       "integrity": "sha512-DaDeUkXZKjdGhgYaHNJTV9pV7Y9B3b644jCLs9Upc3VeNGg6LWARAT6O+Q+/COo+2gg/bM5rhpMAtf70WqfBdQ==",
       "dev": true,
+      "peer": true,
       "requires": {}
     },
     "@csstools/css-syntax-patches-for-csstree": {
@@ -4151,7 +4155,8 @@
       "version": "3.0.4",
       "resolved": "https://registry.npmjs.org/@csstools/css-tokenizer/-/css-tokenizer-3.0.4.tgz",
       "integrity": "sha512-Vd/9EVDiu6PPJt9yAh6roZP6El1xHrdvIVGjyBsHR0RYwNHgL7FJPyIIW4fANJNG6FtyZfvlRPpFI4ZM/lubvw==",
-      "dev": true
+      "dev": true,
+      "peer": true
     },
     "@eslint-community/eslint-utils": {
       "version": "4.9.0",
@@ -4517,7 +4522,8 @@
       "version": "8.15.0",
       "resolved": "https://registry.npmjs.org/acorn/-/acorn-8.15.0.tgz",
       "integrity": "sha512-NZyJarBfL7nWwIq+FDL6Zp/yHEhePMNnnJ0y3qfieCrmNvYct8uvtiV41UvlSe6apAfk0fY1FbWx+NwfmpvtTg==",
-      "dev": true
+      "dev": true,
+      "peer": true
     },
     "acorn-import-attributes": {
       "version": "1.9.5",
@@ -5085,6 +5091,7 @@
       "resolved": "https://registry.npmjs.org/eslint/-/eslint-9.36.0.tgz",
       "integrity": "sha512-hB4FIzXovouYzwzECDcUkJ4OcfOEkXTv2zRY6B9bkwjx/cprAq0uvm1nl7zvQ0/TsUk0zQiN4uPfJpB9m+rPMQ==",
       "dev": true,
+      "peer": true,
       "requires": {
         "@eslint-community/eslint-utils": "^4.8.0",
         "@eslint-community/regexpp": "^4.12.1",
@@ -5716,9 +5723,9 @@
       }
     },
     "jquery": {
-      "version": "3.7.1",
-      "resolved": "https://registry.npmjs.org/jquery/-/jquery-3.7.1.tgz",
-      "integrity": "sha512-m4avr8yL8kmFN8psrbFFFmB/If14iN5o9nw/NgnnM+kybDJpRsAynV2BsfpTYrTRysYUdADVD7CkUUizgkpLfg==",
+      "version": "4.0.0-rc.1",
+      "resolved": "https://registry.npmjs.org/jquery/-/jquery-4.0.0-rc.1.tgz",
+      "integrity": "sha512-ima3YNbwR733XSQ/yFbO4Kjq7Z01feW8BmzZ4VjuuFvWVpGdjXSpmOJZRaehA4V60Aj97HsHNRnDM188c8pHHw==",
       "dev": true
     },
     "js-string-escape": {
@@ -5951,8 +5958,7 @@
       "version": "3.3.11",
       "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.11.tgz",
       "integrity": "sha512-N8SpfPUnUp1bK+PMYW8qSWdl9U+wwNWI4QKxOYDy9JAro3WMX7p2OeVRF9v+347pnakNevPmiHhNmZ2HbFA76w==",
-      "dev": true,
-      "peer": true
+      "dev": true
     },
     "natural-compare": {
       "version": "1.4.0",
@@ -6114,8 +6120,7 @@
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
       "integrity": "sha512-xceH2snhtb5M9liqDsmEw56le376mTZkEX/jEb/RxNFyegNul7eNslCXP9FDj/Lcu0X8KEyMceP2ntpaHrDEVA==",
-      "dev": true,
-      "peer": true
+      "dev": true
     },
     "picomatch": {
       "version": "4.0.2",
diff --git a/package.json b/package.json
index 1553d7d..2005a28 100644
--- a/package.json
+++ b/package.json
@@ -30,10 +30,10 @@
     "eslint-config-jquery": "^3.0.0",
     "eslint-formatter-pretty": "^7.0.0",
     "globals": "^16.0.0",
-    "jquery": "^3.7.1",
+    "jquery": "4.0.0-rc.1",
     "jsdom": "^27.0.0"
   },
   "peerDependencies": {
-    "jquery": "^1.7.0 || ^2 || ^3"
+    "jquery": "^1.7.0 || ^2 || ^3 || ^4"
   }
 }