Not so long ago, in the working list, the topic of using the letter “” in the documentation and posts was discussed.
The discussion dragged on for several months ...
Realizing the importance of the problem, I wrote a
fixator on Node.js.With it, you can check and restore the letter "e" in any text format.
Installation
npm install eyo -g
')
Recovery
eyo file.txt > file_yo.txt eyo https://habrahabr.ru > habr_yo.html
Check
eyo --lint file.txt eyo --lint https://habrahabr.ru

Regardless of the attitude to the letter "e", it is worth noting some features.
In regular expressions, in the "e" ranges, you must specify separately:
function hasRussianLetters(text) { return text.search(/-/i) > -1; }
When sorting words, the result is not obvious:
["", "", "", ""].sort();
References: