Here are some questions I have and some remarks.
Pourquoi ne pas avoir utilisé un library pour le drag an drop ?
Il serrait plus simple d’utiliser une library disposant d’une bonne API pour simplifier l’ajout de nouvelle fonctionnalité (colummn drag & drop, etc)
A little problem with the onClick
I wanted to create a quick edit by simply clicking on the task, so I put a link to the ‘js-modal-large’ css class and insert my divs in it but now onClick is called on the whole document and returns the target element (div), I understand it’s for performance reasons, so I added a little addEventListener until I find a more optimized fix.