$_GET[“q”] … $q==1 echo “yadda yadda yadda!” … Comes back undefined. localhost using XAMPP

Question

So the function is pretty simple(Not so much for me!), it takes an HTML form, and upon selecting a drop down option, it sends the option value to index.php and get's a response, based on the response it changes the content of the page! But it keeps coming back "Undefined"... I am running the webpage off of localhost/index.php with XAMPP.

    <div id="currentactivity">
      <table width="800" border="1">
      <tr><td colspan="2"><br /><center><h2>Dynamically change page content with Ajax &amp; PHP</h2></center></td>
      </tr>
      <tr>
      <td width="200">
      <form>
      <select name="Data" onChange="showData(this.value)">
      <option value="">Select page Content:</option>
      <option value="1">Page Content 1</option>
      <option value="2">Page Content 2</option>
      <option value="3">Page Content 3</option>
      <option value="4">Page Content 4</option>
      </select>
      </form>
      </td>
      <td><div id="showData">Use the select box to change page content</div></td>
      </tr>
      </table>
    </div>

Below is the JavaScript function. (I currently have it run through an outside .js script, but I have tried the function straight out of the section and it did the exact same thing!)

function showData(str)
{
if (str=="")
  {
  document.getElementById("showData").innerHTML="";
  return;
  }
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("showData").innerHTML=xmlhttp.resonseText;
    }
  }
xmlhttp.open("GET","index.php?q="+str,true);
xmlhttp.send();
}

And the below is my PHP page (Yes this is directly ripped off of a tutorial website!)

<?php
$q=$_GET["q"];

if ($q==1) {echo "Page Content 1 would be shown";}
if ($q==2) {echo "Page Content 2 would be shown";}
if ($q==3) {echo "Page Content 3 would be shown";}
if ($q==4) {echo "Page Content 4 would be shown";}
?>

Answer 1

这个xmlhttp.resonseText应该是xmlhttp.responseText

Answer 2

I believe that the following html:

<select name="Data" onChange="showData(this.value)">

might work on some but not all browsers... I think you should use this instead:

<select name="Data" onChange="showData(this.options[this.selectedIndex])">