Perform function in php based on onChange javascript value passed before performing anything

I have a page (see link below) in which if you type something in the Part_no field, it performs JS function. The JS function does a search thru a db with PHP Mysql and if it finds matching value, it auto populates the other columns. That works fine. However, if it finds nothing, it still performs the function and populates with nothing. That is the flaw. I want it to Do NOTHING if it doesn't find a matching value. (still writing this question.. please hold)

function changeAllProdSelections(str) {
if (str == "") {
//document.getElementById("selections").innerHTML = "";
// location.reload();
return;
} else {
xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
document.getElementById("selections").innerHTML = this.responseText;
}
};
xmlhttp.open("GET","changeAllProdSelections.php?q="+str,true);
xmlhttp.send();
}
}

if (this.readyState == 4 && this.status == 200) {

Should be:

if (this.readyState == 4 && this.status == 200 && this.responseText != "") {

Then it won't do anything if the response is blank.

I tried it and it still performs function. I've attached the files but also have FTP access above.

(If you can fix it for me or send answer with an open ticket (I think you'll fix it fast), then that's ok with me. Thank you)

Hold on. Let me try something frst.

ok. didn't work fo me. Let me know if you can just do it. Thank you.

Call me... I'll need more details on what exactly you want in the different scenarios.

I'll can try calling. But....here's an example part no. for it to auto populate: ST0005. I only care about the function named changeAllProdSelections(). If there's something already there, and you enter nothing, it leaves what was there. That's fine. If you input something that doesn't exist, make it do absolutely nothing (or just don't run that function) including not changing what was there. Just nothing.

Once I see that, I can probably fix the rest. Thanks.

I think if you add the code I suggested above and then update the changeAllProdSelections.php page and add this on line 10:

<?php

if (!$WADAcac_prod_subcategory_leveltwo_NEW->TotalRows) die();

?>

That would probably do it.

Thanks. It put me in the right path even though the function still runs. So, now I have it so that the input fields just come back with all data when a part no. is not found. I think that's fine to show my boss for now.