The `SpinBox` docs show an example of using a spinbox with a RegularExpressionValidator. In some cases, the item strings may come from user input or other sources (e.g. translated strings, in which case we don't whether those strings are still suitable for RegExp), in which case, it'd be a very good idea to escape the strings before passing them to the RegularExpressionValidator.

RegExp.escape() would be very useful in this case.

See also RegExp.escape() documentation at MDN https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/escape