Q:

javascript to run onload and onchange

I have a javascript that runs using the onchange event when a user enteres a value into an input box. 
The script is 
<script type="text/javascript">  
  function showUser(userNumber, str)  
  {  
    if (str=="")  
    {  
      document.getElementById("txtHint" + userNumber).innerHTML="";  
      return;  
    }    
    if (window. XMLHttpRequest)  
    {// code for IE7+, Firefox, Chrome, Opera, Safari  
      xmlhttp=new XMLHttpRequest();  
    }  

    xmlhttp.onreadystatechange=function()  
    {  
      if (xmlhttp.readyState==4 && xmlhttp.status==200)  
      {  
        //document.getElementById("txtHint" + userNumber).innerHTML=xmlhttp.responseText; 
        var responseText = xmlhttp.responseText; 
        var description = responseText; 
        var warehouse = ""; 
        var sellingUnits = ""; 
        if (responseText.indexOf("NOT A VALID") == -1) 
        { 
          description = responseText.substring(12, responseText.indexOf(",Warehouse:"));  
          warehouse = responseText.substring(responseText.indexOf(",Warehouse:")+11, responseText.indexOf(",SellingUnits:"));  
          sellingUnits = responseText.substring(responseText.indexOf(",SellingUnits:")+14);  
        } 

        document.getElementById("whse" + userNumber).innerHTML = warehouse;  
        document.getElementById("txtHint" + userNumber).innerHTML = description;  
        document.getElementById("su" + userNumber).innerHTML = sellingUnits; 

      }  
    }  
    xmlhttp.open("GET","getdata1.php?q="+str,true);  
    xmlhttp.send(); 
  } 
</script> 

and the form is 
<form name="orderform" id="orderform" action="newsale.php" method="post">

<table border=1>    

<tr>
<td>Product Code</td>
<td>Description</td>
<td>Warehouse</td>
<td>Selling Units</td>
</tr>
<tr id="r1">  
    <td width=100>
        <input size=10  type=number id=sku1 name=sku1 value="1182" onchange="showUser(1, this.value)">
    </td>
    <td width=280>
        <div align="left" id="txtHint1">&nbsp;</div>
    </td>
    <td width=100>
        <div align="left" id="whse1">&nbsp;</div>
    </td>
    <td width=100>
        <div align="left" id="su1">&nbsp;</div>
    </td>
</tr>
<tr id="r2">  
    <td>
        <input size=10  type=number id=sku2 name=sku2 value="1183" onchange="showUser(2, this.value)">
    </td>
    <td>
        <div align="left" id="txtHint2">&nbsp;</div>
    </td>
    <td>
        <div align="left" id="whse2">&nbsp;</div>
    </td>
    <td width=100>
        <div align="left" id="su2">&nbsp;</div>
    </td>
</tr>
<tr id="r3">  
    <td>
        <input size=10  type=number id=sku3 name=sku3 value="1174" onchange="showUser(3, this.value)">
    </td>
    <td>
        <div align="left" id="txtHint3">&nbsp;</div>
    </td>
    <td>
        <div align="left" id="whse3">&nbsp;</div>
    </td>
    <td width=100>
        <div align="left" id="su3">&nbsp;</div>
    </td>
</tr>
<tr id="r4">  
    <td>
        <input size=10  type=number id=sku4 name=sku4 value="1046" onchange="showUser(4, this.value)">
    </td>
    <td>
        <div align="left" id="txtHint4">&nbsp;</div>
    </td>
    <td>
        <div align="left" id="whse4">&nbsp;</div>
    </td>
    <td width=100>
        <div align="left" id="su4">&nbsp;</div>
    </td>
</tr>
</table>
</form>

So as mentioned, the script works perfectly for the onchange event.  I have defined values for each input box, when the page loads I want the script to be called and executed for those values.  Once the user changes the values it must rerun for the new value. 
I tried putting the following script in the header section of the page, but it is inconsistent in the rows it works for.  My skills arent great so I feel I am missing something small. 
<script type="text/javascript">  
window.onload = function() { 
showUser(1, document.getElementById("sku1").value);
showUser(2, document.getElementById("sku2").value);
showUser(3, document.getElementById("sku3").value);
showUser(4, document.getElementById("sku4").value);
}
</script>

Any advice is appreciated as always. 
Thanks and Regards,
Ryan

A:

Long shot, try this in your existing code.  Declare xmlhttp as a local variable to the function. 
<script type="text/javascript">  
  function showUser(userNumber, str)  
  {  

    var xmlhttp = null; // line aded. 
    if (str=="")  
    {  
      document.getElementById("txtHint" + userNumber).innerHTML="";  
      return;  
    }    
    if (window. XMLHttpRequest)  
    {// code for IE7+, Firefox, Chrome, Opera, Safari  
      xmlhttp=new XMLHttpRequest();  
    }  

    xmlhttp.onreadystatechange=function()  
    {  
      if (xmlhttp.readyState==4 && xmlhttp.status==200)  
      {  
        //document.getElementById("txtHint" + userNumber).innerHTML=xmlhttp.responseText; 
        var responseText = xmlhttp.responseText; 
        var description = responseText; 
        var warehouse = ""; 
        var sellingUnits = ""; 
        if (responseText.indexOf("NOT A VALID") == -1) 
        { 
          description = responseText.substring(12, responseText.indexOf(",Warehouse:"));  
          warehouse = responseText.substring(responseText.indexOf(",Warehouse:")+11, responseText.indexOf(",SellingUnits:"));  
          sellingUnits = responseText.substring(responseText.indexOf(",SellingUnits:")+14);  
        } 

        document.getElementById("whse" + userNumber).innerHTML = warehouse;  
        document.getElementById("txtHint" + userNumber).innerHTML = description;  
        document.getElementById("su" + userNumber).innerHTML = sellingUnits; 

      }  
    }  
    xmlhttp.open("GET","getdata1.php?q="+str,true);  
    xmlhttp.send(); 
  } 
</script> 

