get childNodes index of removed nodes

[marcelklehr]

Hey,

over at http://github.com/marcelklehr/dom-ot it would be nice to have a way to find out the index a removed dom node had in its parent's childNodes NodeMap. Currently, there's only oldPreviousSibling, however, if that has also been removed, there's no way to find out which index it had.

[Kequc]

It would be useful to see index information on nodes in a summary.

div.number-1 [index: 0]
div.number-2 [index: 1] (removed)
div.number-3 [index: 2] (removed)
div.number-4 [index: 1] (added)

That would almost make oldPreviousSibling obsolete.

[Kequc]

The way MutationObserver works, from which MutationSummary is built. The MutationObserver returns individual removal records but sometimes many at the same time.

var divs = document.querySelectorAll('div');
divs[2].remove();
divs[1].remove();

You'll receive an array containing both removals from the MutationObserver. divs[2]'s mutation previousElementSibling would be div[0] and div[1]'s mutation previousElementSibling would also be div[0]. Both the same.

You could then do some maths to figure out what the indexes were, but not necessarily the order they were in before removal. MutationSummary though, does add a little bit more complexity. A lookup of the old positioning should be possible.