I am trying to build a web app where users can use OpenLayers to draw features and then save them either as a download or write to a file on the server which I can collect when I need it. I am happy with the OL3 bit so far. From reading around it seems AJAX is the way to do this so I have managed to included a button in my HMTL which runs a function that runs a php file to create a new file.I was pretty happy that I managed to get an empty text file as a start. So how do I get that file to contain the JSON information? I assume I need to send it from the JS world to PHP somehow? I have seen a answer using jquery which sends data though post but I can't figure out how to run that script on my page.
The Function
function loadXMLDoc()
{
var xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET","run.php",true);
xmlhttp.send();
}
</script>
The button
<button type="button" onclick="loadXMLDoc()">do something</button>
The PHP file (run.php)
<?php
$myfile = fopen("store/anothernewfile.geojson", "w") or die("Unable to open file!");
$txt = ['lyr_site'];
fwrite($myfile, $txt);
fclose($myfile);
?>