This is related to the same problem as this question:
When using escaped characters in the <input> pattern attribute, Firefox throws these errors to the console:
Unable to check
<input pattern='^[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEFa-zA-Z\s\'-]{1,50}$'>because the pattern is not a valid regexp: invalid identity escape in regular expression
So when using the pattern attribute on an <input> field, the unicode characters no longer need to be escaped. In that case the user simply needs to stop escaping their characters and change \@\% to @%, problem solved.
I've got this somewhat more complicated regex pattern, what do I change it to to work in Firefox?
<input type="text" pattern="^[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEFa-zA-Z\s\'-]{1,50}$">
Essentially it's allowing for any string between 1..50 characters in length as long as all the characters are within these ranges:
- \u00A0-\uD7FF
- \uF900-\uFDCF
- \uFDF0-\uFFEF
- a-z
- A-Z
as well as whitespace, apostrophes and hyphens. A quick search sees the \u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEFa part of it fairly widely used in all sorts of regexes. I just don't see exactly what to use instead of the escaped unicode character references here.