Bundles all your JS files into one file.Point your html script src at this file, and put all your files in the $files array. Turn devMode on if you're updating your js files a lot and it will regenerate if any are newer than the current bundle.

BundleJS.php

<?php

    //
    // Edit these bits
    //

    $bundleFileName = __DIR__.'/_bundle.js';
    $devMode = true;
    $files = array(

    );
    if(!$files)
        $files = getLocalFiles();

    $files = makeRelative($files); // Comment out if you don't want $files to be relative to the script

    //
    // Create and/or throw out the file
    //

    if(!is_readable($bundleFileName) || ($devMode && isOld($bundleFileName, $files)))
        createBundle($bundleFileName, $files);

    outputJS($bundleFileName);

    //
    // Functions
    //

    function outputJS($file) {
        if(strstr($_SERVER['HTTP_USER_AGENT'],'MSIE')==false) {
            header('Content-type: text/javascript');
            header('Content-Disposition: inline; filename=\'download.js\'');
            header('Content-Length: '.filesize($file));
        } else {
            header('Content-type: application/force-download');
            header('Content-Disposition: attachment; filename=\'download.js\'');
            header('Content-Length: '.filesize($file));
        }
        header('Expires: Fri, 01 Jan 2010 05:00:00 GMT');
        if(strstr($_SERVER['HTTP_USER_AGENT'],'MSIE')==false) {
            header('Cache-Control: no-cache');
            header('Pragma: no-cache');
        }
        include($file);
    }

    function isOld($bundleFile, array $files) {
        foreach($files as $file)
            if(filemtime($file) > filemtime($bundleFile))
                return true;
        return false;
    }

    function makeRelative($files) {
        foreach($files as $i => $file)
            $files[$i] = __DIR__."/$file";
        return $files;
    }

    function getLocalFiles() {
        $allFiles = scandir(__DIR__);
        $files = array();
        foreach($allFiles as $file)
            if($file[0] !== '_' && substr($file,-3)==='.js')
                $files[] = $file;
        return $files;
    }

    function createBundle($filename, array $files) {
        $nl = "\n\r";
        $date = date('Y-m-d H:i:s');
        $output = "// Created: $date $nl";
        foreach($files as $file)
            $output .= file_get_contents($file).$nl;
        file_put_contents($filename, $output);
    }