This script is throwing this error every half second:
Uncaught InvalidStateError: An attempt was made to use an object that is not, or is no longer, usable. signals.js:9
req.onreadystatechange signals.js:9
update_table signals.js:26
req.onreadystatechange
This is signals.js - I want it to reload every 5 seconds and if there is new content, to trigger the "Sound" alert.
function update_table()
{
var old_table = document.getElementById('signals').innerHTML;
var req = new XMLHttpRequest();
req.onreadystatechange = function(){
if(req.status == 200)
{
if(req.readyState == 4)
{
var new_table = req.responseText;
alert(old_table);
alert(new_table);
if(old_table != new_table)
{
//play sound
alert("Sound!");
}
alert("Refresh!");
setTimeout(update_table, 5000);
}
}
}
var link = "table.php?refresh=true";
req.open("GET", link, false);
req.send();
}