too long

Question

So maybe I'm just having a brain hiccup, idk. But it seems like this should work but it doesn't.

The Intent

Build a string throughout a page for use later on in the app page.

The Question

How do we store a string in a way that we can add to it with a function several times before using the resulting value of the string? Is there a better way to do this with a function than to use a variable?

A Non-Working Example

<?php
$testNG = "";
function testNG($tng){
  $testNG .= $tng;
  return $testNG;
}
testNG("hello!!");
?>
<h2><?= $testNG; ?></h2>

As always, thank you all for contributing to making the online world a much more efficient place!

Edit

An example purpose for this would be to allow Javascript to be aggregated into a variable so that it can be created near the elements it effects, then placed in a section before the </body>

<div id="rating"></div>
<?php testNG("$('#rating').rating();"); ?>
<p>blah blah</p>
...

...
</footer>
<?php
if($testNG != ""): ?>
<script>
<?= $testNG; ?>
</script>
<?php endif; ?>

Answer 1

One way to do it is to declare $testNG as static within your function rather than using a global variable. From the PHP manual:

A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope.

So each time you call the function it will add the input to whatever's already there.

<?php

function testNG($tng = '') {
    static $testNG = '';
    return $testNG .= $tng;
}

testNG("hello!!");
testNG(" world!!");
testNG(" etc.");
?>
<h2><?= testNG(); ?></h2>

Demo at 3v4l.org