Timed alert box pop up for website? [duplicate]

Question

For my website I would like an alert box message to appear 4 seconds after the page is opened. I cant figure out how to do this as the timed function works if a button is clicked but I would like the alert box to pop up automatically withoutt any user input/button and then shut when the user clicks "okay"...

Any ideas or posts related to this topic would be great help!

Thanks

Answer 1

<script type = "text/javascript">
window.onload=function(){setTimeout(showPopup,4000)};

function showPopup()
{
   //write functionality for the code here
}
</script>