Question

I’m working on a little project, but I’m stuck and don’t know what I’m doing wrong.
I use Ajax to call a php-script that updates a MYSQL-row.

The javascript:

function savecust()
{
if (window.XMLHttpRequest)
  {
  xmlhttp=new XMLHttpRequest();
  }
else
  {
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("custdetails").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","./ajax/savecust.php?id=" + document.getElementById('id').value,true); //More arguments should still be passed.
xmlhttp.send();
}

If I remove the document.getElementById('id').value the script works and does what is is supposed to do. (I get the response from the PHP, obviously

I load the script in the head of the page along with some other scripts:

<script src="js/custedit.js" type="text/javascript"></script>

This is how I call the script:

<input type='button' onclick='savecust()' value='Save' />

Any help would be greatly appreciated ;-).

Thanks!

EDIT

• The div where the content should go, exists.
• The PHP-scripts returns an error for now (because it doesn’t get all the required parameters)
• The content (and textfield with id: ‘id’) is loaded by another script. Is this a problem? If you look at the source in a browser the textfields are not there. They are however visible in the browser.

EDIT 2

So, I ran this test on top of my script:

var thisid = 'id';//should get info from <input type='text' name='id' />
var T = document.getElementById(thisid);
if (T) {
     alert("element exists" + T.value);
} else {
alert("nothing to be found");
}

It is indeed unable to find the element. This pointed me in the right direction.
<input type='text' name='id' />is inserted by another Ajax-script. So I think the second script is unable to find it.

How do I solve this?

Answer 1

You cannot access an element property if it does not exist.

Perhaps a test:

var thisid = 'id';//whatever it REALLY is...
    var T = document.getElementById(thisid);
    if (T) {
         alert("element exists" + T.value);
    }