How to pass comma separated multi select values to the url on form submit
<p>I have a basic GET form in my project that is used to filter through posts created by users. When I submit the form the values from the multiple select input are appended to the url like so:</p>

<pre><code>project.dev/?maps[]=1&amp;maps[]=2&amp;maps[]=3
</code></pre>

<p>As you can see, the values are passed to the url via three separate key value pairs... However, I would like to know how to append the values to the url in the following format:</p>

<pre><code>project.dev/?maps=1,2,3
</code></pre>

<p>Thanks in advance.</p>