[Solved] $(document).on doesn’t work

I don’t think there’s ever been a version of jQuery that supported what you’re doing in the new code.

Your code is calling cache, then bindEvents. You have this in cache:

this.postForm = $('#postForm');

and this in bindEvents:

$(document).on('submit', this.postForm, this.createPost);

So that means you’re calling on and passing it an event name, a jQuery object, and a function.

Looking at the documentation, there’s no signature of on that allows a jQuery object as the second argument.

I see that you’ve now posted your old code, which was using a selector string there, which does indeed work via event delegation:

$(document).on('submit', '#postForm', this.createPost);

If you want to handle the submit on the element itself without using delegation, then of course it would be:

this.postForm.on('submit', this.createPost);