<!DOCTYPE html>
<html lang="en-US">
<body>
<details ontoggle="myFunction()">
<summary>List to be purchased</summary>
<ul>
<li>Apple - 1kg</li>
<li>Banana - 2 Nos</li>
<li>Indian Gooseberry - 10 Nos</li>
</ul>
</details>
<script>
function myFunction(){
alert("You are toggling");
}
</script> </body>
</html>