PHP active section after page refresh - php

Question

I am trying to create a one page navigation menu in PHP. The reason I want it to be in PHP is because I can add other code later and I want the user to be on the same page even after a refresh.
I have an unordered list with generated list items. The list items are generated with an array.
(I want the key/values separated because the actual code will be different. This is just an example.)
$nav = array(
"home" => "home",
"about" => "about",
"contact" => "contact"
);
echo '<ul>';
foreach( $nav as $id => $name )
{
echo '<li>'.$name.'</li>';
}
echo '</ul>';
// outputs:
<ul>
<li>home</li>
<li>about</li>
<li>contact</li>
</ul>
Then I want some divs to be the sections
foreach( $nav as $s_id => $s_name)
{
echo '<div id="'.$s_id.'">Some section text</div>';
}
Now I need to know how can I set the display to either block or none based on current id active?

Answer 1

While I personally think this is more of a job for JavaScript, in the question and a comment above you specify that you want to do this in PHP. In that case those anchor tags will need to be actual links to the page. For the sake of this example I'll assume the page is called index.php. (If it's something different, just use whatever your page is.)
Update the anchors to be links to the page with query string parameters:
<li>home</li>
<li>about</li>
<li>contact</li>
Then in your PHP code you'd determine which one is "active" by the active query string parameter. Start with a default of "home" in case no parameter is specified (it's the user's first time on the page):
$active = "home";
if (isset($_GET["active"])) {
$active = $_GET["active"];
}
Then when rendering the <div> elements you can specify their style:
foreach( $nav as $s_id => $s_name)
{
echo '<div id="'.$s_id.'" style="display:'.($s_id == $active ? "block" : "none").'">Some section text</div>';
}