Testing morphdom with jsdom is tricky.

[ioquatix]

Hi, thanks for creating morphdom.

It looks like testing morphdom with jsdom is quite tricky, e.g. https://runkit.com/autosponge/morphdom-jsdom-example

Having to set up a global document before invoking morphdom is tricky when there are lots of tests which might use different doms.

Might I propose adding an option, e.g. morphdom(..., ..., document: dom.window.document) or something similar that allows us to inject this into the individual calls? Alternatively, maybe we can extract it from the first argument?

I see some additional discussion here: #98

Another idea is to introduce a class which contains the state.

e.g.

morphdom = new Morphdom(document);
morphdom.morph(...)

In my own code, I have something like this:

  constructor(window) {
    this.window = window;
    this.document = window.document;

This makes testing using jsdom extremely easy.

[ioquatix]

I found one way to work around this is pre-constructing the fragment, rather than providing HTML:

	createDocumentFragment(html) {
		return this.document.createRange().createContextualFragment(html);
	}
	
	update(id, html, options) {
		let element = this.document.getElementById(id);
		let fragment = this.createDocumentFragment(html);
		
		morphdom(element, fragment);

This avoids morphdom having to interact with doc internally. Not sure if there are any performance problems with this approach?

[ioquatix]

Unfortunately that approach doesn't always work, sometimes createElementNS is invoked regardless.