I would really like to know specifics on your criticism of DOM. I've seen a lot of people complain about DOM over the years, but I've never heard anything specific.
Back to the question:
Traversal: Historically we had 4 methods to get an element: by its id, name, tag, and class; yet there was no general method to get an element by value of its attributes until Selectors API brought querySelector. IMO it was one the most important things that pushed the community towards jQuery back in the day.
Manipulation: Up until recently one couldn't remove an element without referencing its parent, that is, you have to use removeChildNode, or replace, or innerHTML, or other methods of the parent. Now they added .remove() that is only supported in the evergreen browsers. Replacing or inserting nodes operates on the same principles and is a hell of its own that makes people opt for re-generating nodes instead of shuffling the existing ones.
Generation: For years now we have been relying on non-standard innerHTML for element generation because the only way DOM allows to do it is to create each element with createElement and then set attributes one by one. It's a ridiculously low level api considering our use cases. Hence, we got the whole templates/jsx movement today.
Modularity: Ain't there. In order to truly "componentize" our apps we have to wait for something like Shadow DOM because there is no way to guaranty that one part of the page won't affect the other in today's DOM.
All in all, DOM wasn't meant for what we are trying to use it today and for a long time it has been playing catch with browsers implementing ad-hoc solutions to new problems.
Because I look at all the GUI toolkits out there (and in the last twenty years I've used a LOT of different ones), and none of them are idealistically "good". I don't see anything particularly special about other toolkits that makes DOM look particular bad. In fact, I tend to think of DOM as being pretty good in comparison, if only for the fact that it works on everything.
"createElement and then set attributes one by one" is no different than any other toolkit. They pretty much all have a simple, static editor syntax for doing bulk element creation and attribute setting, and then a verbose API for dynamic element creation. It's low level because your use case is not the only use case it needs to support. I've seen--and built--a bunch of systems that have tried to simplify it and it always loses something in translation.
So maybe you're complaint isn't with DOM. Maybe you just don't like user interface programming in general.
That's because my whole point was to elaborate on the statement I made in the first comment:
>The legitimate grievances associated with JS over the years were due to the browser APIs and first of all DOM,
People who were complaining about web dev and JS over the years were mostly doing it because of the browser APIs and DOM, hence my recollection of recent history. And of course I do point out what was fixed, and I said from the start that it's far better now than it was before. I'm rooting for VanillaJS after all.
I cannot comment on other GUI toolkits since I don't work with them. You may be right that they too are low level, and I wholeheartedly you're right about DOM being better, because I hope DOM with Web Platform replaces them all one day. That doesn't exempt DOM from criticism though.
Technically DOM still doesn't have API for bulk element creation since innerHTML/insertAjacent comes as a separate API which is still a working draft. But that's just details.
There is another problem somewhat related to DOM being low level. Although it has to do with the browser implementations rather than the standard, it's still a problem for the end user, and the user is going to blame it on the web/JS being bad in general. That is performance. As it was mentioned here, DOM is separated from JS engine in browsers. Calls to DOM from JS are a lot more expensive than calls inside the engine. This gave rise to the whole Virtual DOM movement we see taking over the web dev. It's not just the verbosity of low level DOM that pushes people towards React and such, but the fact that at the end of the day their approach of mimicking DOM in the engine and limiting the DOM calls turns out to be more performant that the low level manipulations we do directly on the DOM.
Consider the following scenario. You have two handlers on an event that both change the DOM and may result in cancelling each other. With the "raw" DOM you'll end up calling DOM at least twice (and changing it twice if no debouncing is used), whereas Virtual DOM both times calls to, well, its "virtual" DOM (which is a lot cheaper) and by the time it gets to its next cycle of updating the "real" DOM it may not need to change anything or do it once. These optimizations are hard to implement without resorting to a virtual DOM of one sort or another.
Sort of. Calls to DOM from JS are a few dozen machine instructions for the call itself in modern browsers; a little more if lots of arguments are involved. The slowness is what the DOM implementation actually has to _do_ as a result of the call. If you write a loop in which you repeatedly modify styles and then ask for geometry information, then the only options an implementation has are to provide stale geometry information (the virtual DOM approach!) or end up with that loop being a lot slower than asking for all the geometry information up front and then doing your modifications.
We can have a useful discussion about whether it should be possible to ask for stale geometry information, but that has nothing to do with calls from JS into the DOM per se; a DOM implemented in JS but exposing the same API as the current DOM would have _exactly_ the same problem in that regard.
What got me first thinking about the cost of DOM calls were benchmarks we did back when we were building polyfills for IE6-IE8 to support new HTML5 APIs. One example in particular--mimicking data attributes. Our lib would hold a mapping between DOM elements and attached data attributes (as simple objects) and it would be significantly faster than using native element.dataset. While dataset isn't as simple as plain JS object, it's not much complicated either, and to my knowledge changing it doesn't cause reflows or repaints, so I expected it to be slower but not very much; hence, I concluded that the additional speed came from avoiding the DOM call itself. Since then I've been cautious about DOM and tried to cache whatever came from it and was supposed to be used repeatedly.
So you have to implement it as a Proxy, so it can capture arbitrary property assignments, including for properties it doesn't have yet, and do the corresponding setAttribute calls. Unfortunately, once you're a Proxy your gets end up somewhat slow too. Partly this is because JITs haven't optimized proxies that much, and partly it's because they're rather hard to optimize in the best of circumstances.
I expect that the actual implementations of dataset are not as fast as they could be if they used scripted and inlinable proxy handlers _and_ the JITs had implementations for those. But there's still a lot more work involved in dataset than a plain object, especially if you have a small number of property names in practice so the plain object doesn't have to convert to dictionary mode or anything like that.... Even if dataset were implemented on top of a pure-JS DOM implementation (which exist), it would be a lot slower than just a simple object, unfortunately.
[1]https://jsperf.com/dataset-vs-getattribute-and-setattribute/...
But note that in microbenchmarks you are likely to get some confusing effects. For example, in Firefox this microbenchmark:
document.getElementById('test').getAttribute('data-set')
1) getAttribute is known to be side-effect free when called with a string argument, its return value is not used, the call can be dead-code eliminated.
2) getElementById is known to be side-effect free when called with a string argument, its return value is not used after step 1, the call can be dead-code eliminated.
3) The get of the "document" property is known to be side-effect free, its return value is not used after step 2, the get can be dead-code eliminated.
So in the end the microbenchmark is measuring how fast the browser can increment a loop counter, and that only because we haven't bothered to try dead-code eliminating that. That's why you get numbers in the billions of operations per second range (comparable to the CPU clock speed; always a dead giveaway that your thing got optimized out). ;)
Note that Firefox will also perform loop-hoisting on all of the above if possible, so even if the return value were assigned somewhere that would not matter: the whole thing would just get hoisted out of the loop.
The setAttribute and "dataset.set = stuff" benchmarks don't have these problems, because those operations are clearly not side-effect free. A sufficiently advanced JIT might be able to determine that earlier iteration assignments are dominated by later ones and eliminate them, but now we're talking quite hard work on the part of the browser.
While we are on the subject, can I ask if there are any performance advantages of using data attributes over custom attributes for storing data in an element? In other words, can adding non-standard attributes to an element cause any deoptimizations? I know that JS engines use hidden classes/object shapes to optimize JS objects, I assumed something similar might be the case for DOM elements, in that case adding non-standard attribute must mean deoptimization.
Every node has a reference to it's parent.
What's the problem with node.parentElement.removeChild(node)?
Being counter-intuitive and verbose. It's but one example of such peculiarities that makes DOM hard to grasp for beginners.
It's node.parentNode.removeChild(node). And the fact that this is even a mistake that can be made, and is made by people all the timem is part of the problem!
"node.remove()" is a lot harder to screw up.
Obviously it can be nice for organization, but that should really fall more on the individual to decide than the spec.