_.isElement

_.isElement is the one node in this whole family you should know about mainly so you don't waste time on it: it always returns False. The docs describe it as "Returns true if object is a DOM element" - the original Underscore.js semantics - but this is a Python port running in a Python process. There is no DOM. The implementation says as much:

def isElement(self):
    """ No use in python
    """
    return self._wrap(False)

Feed it anything - a dict, a string, an image, a list - and the answer is False, every time. That's not a bug you hit intermittently; it's the entire behavior of the node.

The inputs that matter

The schema is a bit of a giveaway that this node is auto-generated boilerplate:

• py_dict - the primary input (*). It's named py_dict because the generator filed isElement under "object" methods, even though the value is discarded entirely.
• Output is a single BOOLEAN, always false.

Why it exists

This is a transparency artifact of how the pack works. The ovum/underscore nodes are generated by walking every method on the bundled underscore3 Python port of Underscore.js and stamping out one ComfyUI node per method. Underscore.js has _.isElement (it checks for a browser DOM element), the port kept a stub for API parity, and the generator dutifully turned the stub into a node. Nobody decided this was a useful node; it's just what the machinery produced. It's the clearest example in the pack of the README's own warning that the underscore family is a work in progress.

The honest take

Don't reach for _.isElement for anything. If you need "is this a real DOM element" - you're in ComfyUI, so you don't. If you were hoping for a general object check, that's _.isObject or _.isDict/_.isDictlike depending on what you mean. Consider _.isElement a placeholder from the port, useful only as a reminder that these nodes were machine-generated and some of them are hollow.

Installing

Ships in comfy-ovum (MIT). ComfyUI Manager → search comfy-ovum → install → restart, or:

cd ComfyUI/custom_nodes
git clone https://github.com/sfinktah/comfy-ovum

No extra dependencies for the underscore nodes - the bundled underscore3 port covers them.

Gotchas

Beyond "it always returns false," the only real risk is wiring it in thinking it does something. It doesn't - and that's honestly the most useful fact in this article. If a workflow you loaded from somewhere includes _.isElement and you were wondering why a branch never fires, now you know: it's not your graph, it's the node.