unexpected identifier with scrolling menù
<p>I'm having trouble with my first html website. I'm trying to create a vertical scrolling menù, and this is my code:</p>

<pre><code>&lt;body onLoad="javascript:startmenu()"&gt;
&lt;div id="header"&gt;
        &lt;div id="logo"&gt;
            &lt;a href="index.html"&gt;&lt;img src="images/logo.jpg" alt="" /&gt;&lt;/a&gt;       
        &lt;/div&gt;      
        &lt;ul&gt;
            &lt;li class="selected"&gt;&lt;a href="index.html"&gt;&lt;span&gt;home&lt;/span&gt;&lt;/a&gt;&lt;/li&gt;
            &lt;li&gt;&lt;a onMouseOver="javaScript:menufunc()"&gt;&lt;span&gt;prodotti&lt;/span&gt;&lt;/a&gt;&lt;/li&gt;
                &lt;li&gt;
                &lt;div id="prod"&gt;
                    &lt;ul&gt;
                    &lt;li&gt; - &lt;a href='http://www.google.com'&gt;Google&lt;/a&gt;&lt;br&gt; &lt;/li&gt;
                    &lt;li&gt; - &lt;a href='http://www.yahoo.com'&gt;Yahoo&lt;/a&gt;&lt;br&gt; &lt;/li&gt;
                    &lt;li&gt; - &lt;a href='http://www.altavista.com'&gt;AltaVista&lt;/a&gt; &lt;/li&gt;
                    &lt;/ul&gt;
                &lt;/div&gt;
                &lt;/li&gt;
            &lt;li&gt;&lt;a href="contact.html"&gt;&lt;span&gt;contatti&lt;/span&gt;&lt;/a&gt;&lt;/li&gt;   
            &lt;li&gt;&lt;a href="about.html"&gt;&lt;span&gt;dove siamo&lt;/span&gt;&lt;/a&gt;&lt;/li&gt;
            &lt;!-- &lt;li&gt;&lt;a href="services.html"&gt;&lt;span&gt;services&lt;/span&gt;&lt;/a&gt;&lt;/li&gt; --&gt;     
        &lt;/ul&gt;
&lt;/div&gt;
</code></pre>

<p>and this is the function:</p>

<pre><code>function startmenu(){
document.getElementById('prod').style.display = "none"; }

function menufunc(){
if(document.getElementById().style.display == "none"){
    document.getElementById().style.display = "block";
} else{
    startmenu();
} }
</code></pre>

<p>but I recive this error: Uncaught TypeError: <i>Cannot read property 'style' of null: [Exception: SyntaxError: Unexpected identifier]</i></p>
