WYSIWYG editor and text selection? How?

Question

JavaScript

Help me figure out how rich text editors on websites handle the task of selecting multiple nodes (for example, we have a piece of text highlighted with a b tag, after this piece there is plain text that is not selected in any way, having only one parent div, like node b ). It wouldn't be a question if I had one node and text inside, but how do I select the text at the intersection of the nodes?
I pick nicedit, but very sluggishly.
What do I need to google to find the answer?

Answer 1

learn.javascript.ru/vydelenie-range-textrange-i-selection

Answer 2

stackoverflow.com/questions/2584301/getselection-surroundcontents-across-multiple-tags