Cache dynamic JavaScript generated by PHP

Question

I use JShrink with a custom function to combine 8 uncompressed JavaScript files to a single compressed (minified) one, like this:

<?php
// Filename: js.php 
header('Content-type: text/javascript');
require_once '../JShrink.php';

function concatenateFiles($files)
{
    $buffer = '';

    foreach($files as $file) {
        $buffer .= file_get_contents(__DIR__ . '/' . $file);
    }

    return $buffer;
}

$js = concatenateFiles([
  'core.min.js', 
  'promise.js', 
  'welcome.js',
  'imagesloaded.js',
  'cropper.js',
  'translate.js',
  'custom.js',
  'masonry.js',
]);

$output = \JShrink\Minifier::minify($js);
echo $output;

Then I call this php file in my index page footer:

<script type="text/javascript" src="<? echo $url ?>/js/js.php"></script>

It is not being cached.

I modify my JS codes daily and I don't like to keep combining them manually, but also I need a way to get the echoed JS code cached, only that code and not all php files on the server.

How can I do this, and how would the cache purge process be?

Thanks in advance.

dkellner · Accepted Answer · 2017-02-18 22:18:01Z

1

In theory, you need to use a header("...") with proper expiration. In practice, that's not working properly. You can spend your life googling for proper examples of "Cache-Control" and "Expires:" and none of what you find will work. So I suggest you to read this:

https://developers.google.com/web/fundamentals/performance/optimizing-content-efficiency/http-caching

ETags are the modern solution to tell the browser when your resource has changed - or not.

answered Feb 18, 2017 at 22:18

dkellner

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2 Comments

tinyCoder Over a year ago

You made my day man, thanks. I followed your note and found this great answer, I hope it helps someone: stackoverflow.com/questions/13197479/…

dkellner Over a year ago

Glad to hear that :) Have a nice optimized data transfer!

Ruben Vincenten · Accepted Answer · 2017-02-18 22:07:26Z

0

If the cache file doesnt exist or if any of the file modification timestamps is later then the cache, render it, then safe it to the cache, then echo the cache or the rendered result.

answered Feb 18, 2017 at 22:07

Ruben Vincenten

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