Validating file extension problem

[siddharth paul]

hii all
in my code i m uploading a file with .doc extension
its working fine and giving alert when extension is not .doc but the problem is when it is different file extension, after the alert it is not clearing the field.

    
function fnChkFile(str){
var ext=document.getElementsByName(str)[0];
if ((ext.value.lastIndexOf('.doc') == -1))
{
alert("Invalid File extension");
ext.value="";   // it is not happening
ext.focus();
return false;
}

return true;
}

[siddharth paul]

using reset as a solution will reset the whole page but i want only file field to be reset.
what are the security restriction for resetting a file field.

[Eric Pascarello]

You can not set the value of the field since it is a security concern.

You can try ext.reset() and see if that works, I am guessing that it will not.

Eric