<p>I have this piece of code in my PHP code:</p>

<pre><code>while ($row = mysqli_fetch_assoc($result))
{
    extract($row);
    echo "&lt;tr&gt;";
    echo "&lt;td bgcolor='#FFFFFF'&gt;&lt;input id='bookArray[]' name='bookArray[]' type='checkbox' value='$book_id' /&gt;$book_id&lt;/td&gt;";
    echo "&lt;td bgcolor='#FFFFFF'&gt;$threat_name&lt;/td&gt;";
    echo "&lt;/tr&gt;";
}
</code></pre>

<p>In HTML page, I want to use jQuery serialize() method to sent array of selected books in bookArray[]. In my JavaScript,</p>

<pre><code>var selectedbooks = $("book_form").serialize();
alert (selectedbooks); 
</code></pre>

<p>In the alert message box, i did not get any value (empty string).</p>

<p>Previously when i am using Prototype, it worked nicely.</p>

You may need to change your PHP as @Tomalak suggests, but you will also need to change your javascript.  To reference a named element use the #name selector:
```
```
var selectedbooks = $('form#book_form').serialize();;
```
```