> You don’t need parent

You do need parent, check this: https://developer.mozilla.org/en-US/docs/Web/API/Node/parent...

> You want sibling nodes otherwise you will have to traverse back to the root node sometimes to find a sibling.

The only need for this is in Node.nextSibling implementation: https://developer.mozilla.org/en-US/docs/Web/API/Node/nextSi...

Where vector<>::find is pretty sufficient.

But in reality (at least in my Sciter) node stores its index in parent's m_children so it is O(1) operation.

Is there source code available online illustrating your more-efficient DOM data-structure ?

How about the + operator in CSS?

And what is wrong with it?

and ~ combinator and :nth-child(n) selector for that matter too.

I'm responding to the claim that you only need the ability to find a sibling for the nextSibling method.