CKFinder 3 upgrade difficulty - php

Question

I'm following the CKFinder 2 to 3 upgrade guide and it's not making much sense. In CKFinder 2, the PHP code provided could be used to generate the JS snippet with appropriate config and params, like this:
require_once 'ckfinder/core/ckfinder_php5.php';
$finder = new CKFinder() ;
$finder->SelectFunction = 'ShowFileInfo' ;
$finder->DisableThumbnailSelection = true;
$finder->RememberLastFolder = true;
$finder->Id = $name;
$finder->StartupFolderExpanded = true;
$finder->Width = $width;
$finder->Height = $height;
echo $finder->CreateHtml();
This code picks up the config and incorporates it into the generated JS.
In 3 this seems to have disappeared entirely - the upgrade guide describes the changes needed in config.php, but there is no indication of how this is ever used since there is no other PHP involved, and it says
It is no longer possible to enable CKFinder on a page from the PHP level
All that is shown is how to create the JS snippet, which does not contain any config, and so will use incorrect settings. There is no indication of how the config properties set in config.php ever get to the JS code - as far as I can see there is no connection at all and no mention of any other PHP files, even though some are provided but not documented.
This makes no sense - PHP can quite happily generate HTML and JS that is run on the page, which is all the old CreateHTML function did. I don't understand why there is no mention of this mechanism since it was how we were supposed to use CKFinder previously - it's as if the migration guide is for some unrelated package!
If I update the config file and use the default JS widget code as suggested, it breaks the page completely, altering the MIME output type so it does not get rendered as HTML and appends this error:
{"error":{"number":10,"message":"Invalid command."}}
The docs cover various fine details of what PHP config settings mean, but nowhere that I've found says how it's ever loaded, triggered or associated with the JS. How is this supposed to work?

Answer 1

Indeed the CKFinder 3 documentation was lacking some important information. We're gradually adding new articles there. Based on topics you mentioned I just added:
Explanation how PHP code that worked for CKFinder 2 can be refactored to plain JavaScript in CKFinder 3. Should look familiar ;)
A table with Configuration Options Migration - JavaScript Settings which should help you with discovering again options like rememberLastFolder