PHP Update using Javascript - php

Question

I have my php file which contains my method to update the database. However, in Javascript how do I make it so every 5 seconds say it "visits" this page so it's contents gets updated.
Here is my update.php file:
<?php include('config.php') ?>
<?php
mysql_query("UPDATE paint SET paint_points='test'") or die(mysql_error());
echo "Updated";
?>
Sorry, I'm not familiar with the terminology.
Thanks

Answer 1

Use the setInterval function with an (a)jax request every 5 secs in javascript:
//syncronized jax:
function myjax() {
var oXhr = new XMLHttpRequest();
oXhr.open("POST", "yourphp.php", false);
oXhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded; charset=utf-8");
oXhr.send(null);
}
//set an interval each 5 seconds to call your myjax method
setInterval(function() { myjax(); }, 5000);
In this example the request is synchronous but it could be asynchronous if you wished so.

Answer 2

The simplest case is to reload the page with:
<script type="text/javascript">
setInterval(function() { location.reload(true); }, 5000);
</script>
You can get fancier if you use an ajax call to fetch the page.

Answer 3

Using jQuery:
(function() {
var updateAgain = arguments.callee;
$.get('/url/to/script.php', function() {
setTimeout(updateAgain, 5000);
});
})();
The advantage of this over setInterval is that it won't start counting to five seconds until the request is finished; this is important if the request takes more than a second or two. It will also stop if a request fails (which may or may not be an advantage).