I want to have a validation function in a .js file that can be called from many different pages. I was trying to design the function so that it would accept an array of element names to be validated. My plan was to loop through each name in the array and check that element's value to make sure it has been completed. If it hasn't been completed (if it is blank), then I would alert the user. So my code would be something like:

function validate(doc, a){
var s;
for(var i = 0; i < a.length; i++){
s = doc.getElementByID(a[i]).value;
if ( s.replace(/ /g, "") == ""){
//generate some sort of warning, etc...
}
}
}

The doc parameter in the example above would be the document object for the calling page, like this:
function do_validate(){
var a = new Array("FirstName", "LastName", "EMail");
validate(document, a);
}

But, when the validate code runs in the .js file, I get an "Object doesn't support this property or method" error on the line "s = doc.getElementByID(..."

I tried renaming the parameter to 'document' instead of 'doc' but, that did not help.

It seems like I might need explicitly "cast" the doc argument as a document, or something like that. But, that isn't done in javascript is it? I am new to javascript so, I am at a loss here.

I apologize for the long post.

Thanks for any help you can provide.
rogdawg