jQuery codebase is pretty ugly, it has written mostly ES5, it is using custom mixin system and is full of weird workarounds for IE. jQuery age was horrible. Yo

jQuery codebase is pretty ugly, it has written mostly ES5, it is using custom mixin system and is full of weird workarounds for IE. jQuery age was horrible. You needed to manually add <script/style/fonts> into HTML. Everything was based on classes and IDs, small change in CSS would brake jQuery functionality. Codebases were poorly organised and often a mixture of PHP and JS that was re-initialised on every form click. If you wanted to use a third party component, you typically needed to pay for it. Before package managers, you got a zip file, or you needed to include script tag to third party domain in specific order, after jQuery and jQuery-UI.