test.svg

<svg xmlns="http://www.w3.org/2000/svg" width="200" height="200">
  <!-- JavaScript code within a <script> tag -->
  <script type="application/javascript">
    <![CDATA[
      // Your JavaScript code here
      function showMessage() {
        alert('Hello, SVG with Script!');
      }
    ]]>
  </script>

  <!-- Rectangle with an onclick event calling the JavaScript function -->
  <rect x="10" y="10" width="100" height="50" fill="blue" onclick="showMessage()" />
</svg>