When the web browser window is resized, the onresize attribute triggers.
Example
You can try to run the following code to implement onresize attribute −
<!DOCTYPE html>
<html>
<body onresize = "display()">
<p>Resize the window to trigger event.</p>
<script>
function display() {
alert("Web browser window resized!");
}
</script>
</body>
</html>