contenteditable
https://medium.engineering/why-contenteditable-is-terrible-122d8a40e480
https://www.bokukoko.info/entry/2017/10/02/191614
https://developer.mozilla.org/ja/docs/Web/API/range
https://developer.mozilla.org/ja/docs/Web/API/Selection
https://www.bokukoko.info/entry/2017/10/08/154950
https://engineering.linecorp.com/ja/blog/contentable-development-of-line-blog-apps/
https://qiita.com/hanaitama-kaz/items/17832369f279ba0e331a
https://note.com/ct8ker/n/n037f6ba3c318
https://github.com/lovasoa/react-contenteditable
Range
#??
2021年の今でも「contenteditableはツライ」は顕在か?