Javascript Hide/Unhide FileUpload on Checkbox Checked

For some reason my check box isnt controlling the fileupload field I have. Can anyone see what is going wrong with this? When I check the box it does nothing and i'm not getting any errors returned?

<script type="text/javascript">
function checkBox() {
    var changeimage=document.forms["myform"]["changeimage"].checked
    if (changeimage) {
        document.forms["myform"]["picupload"].style.display='';
    } else {
        document.forms["myform"]["picupload"].style.display='none';
    }   
}
</script>
...
<input type="checkbox" name="chnageimage" id="changeimage" onclick"checkBox();" />
  <label for="cha开发者_如何学JAVAngeimage"></label>
  <br />
  <label for="picupload"></label>
  Picture
  <input type="file" name="picupload" id="picupload" style="display: none;"/>
  <br />
  <img src="userpics/<?php echo $row['Photo'] ?>" /></p>

Its much better to do this.

Change your HTML checkbox like this. Pass this object of the clicked HTMLElement on the onclick event

<input type="checkbox" name="chnageimage" id="changeimage" onclick="checkClick(this);" />

Now you can change your javascript like this.

function checkClick(objCheckBox) {
    document.getElementById("picupload").style.display = objCheckBox.checked ? 'block' : 'none';
}

No valid value for .style.display takes the value ''. It should be block in this example.

You have a typo at onclick"checkBox();" should be onclick="checkBox();"

You used onclick"checkBox();" instead of onclick="checkBox();" and there is no form element in html.

 <script type="text/javascript">
        function checkBox() {
                             var changeimage=document.forms["myform"]["changeimage"].checked;
                             if (changeimage) {
                                               document.forms["myform"]["picupload"].style.display='';
                                              } else {
                                               document.forms["myform"]["picupload"].style.display='none';
                                              }   
                            }
 </script>
      <form name="myform">
      <input type="checkbox" name="chnageimage" id="changeimage" onclick="checkBox();" />
      <label for="changeimage"></label>
      <br />
      <label for="picupload"></label>
      Picture
      <input type="file" name="picupload" id="picupload" style="display: ;"/>
       <br />
      </form>