Is hidden() a reserved function of javascript
===

Of these two, only gidden() works.

    <span onclick="hidden()">hello</span>
    <span onclick="gidden()">world</span>
    
    <script type="text/javascript"><!--
        function hidden() {
             alert("hello");
        }
        function gidden() {
             alert("world");
        }
    --></script>

Is hidden() a reserved function of javascript? Cause that is the only thing I can think of for this to make sense. If so, what does it do?