How do I check if a variable contains Chinese or Japanese characters? I know that this line works:
if (document.body.innerText.match(/[\\u3400-\\u9FBF]/))
>
.match is a string method. You can apply it to anything that contains string. And, of course, to arbitrary variable.
In case you have something that is not string, most objects define .toString() method that converts its content to some reasonable stringified form. When you retrieve selection from page, you get selection object. Convert it to string and then use match on it: sel.toString().match(...).