Last year, in a React side-project, I had to replace some content in a string with HTML markup. That is not a trivial thing to do with React, as you can't just put HTML as string in your content, unless you want to use dangerouslySetInnerHtml — which I don't. So, I hacked a little code to smartly split my string into an array of sub-strings and DOM elements.

More recently, while working on Translate.Next — the rewrite of Pontoon's translate page to React — I stumbled upon the same problem. After looking around the Web for a tool that would solve it, and coming up short handed, I decided to write my own and make it a library.