Testing for a feature of regex compilation in IE11

Question

I would like to test for Unicode Regex Property Escapes to avoid compiling a broken regular expression in browsers that do not support it (for example IE11). Ideally, I'd like to write something along the lines of:

if (regex supports unicode property escapes) {
    return /\p{Emoji_Modifier_Base}\p{Emoji_Modifier}?|\p{Emoji_Presentation}|\p{Emoji}\uFE0F/gu;
} else {
    return /somereplacementregex/;
}

Is this possible at all? I know there are some feature detection API's but as far as I know there isn't one for regex. Alternatively if there's another way of writing this that won't break the compilation and would throw an error I can catch then that would also be great.

Answer 1

This works in Firefox or Safari; should be okay in IE11:

let regex = /somereplacementregex/;
try
{
    regex = new RegExp ("\\p{Emoji_Modifier_Base}\\p{Emoji_Modifier}?|\\p{Emoji_Presentation}|\\p{Emoji}\\uFE0F", "gu");
}
catch (e) { }
//
// use regex...
console.log (regex);

Answer 2

If you feel comfortable with something like Function or eval, and a try/catch...something like this should work:

try { 
  return new Function('', 'return /\\p{Script=Greek}/u;')() 
} catch(e) { return /asdf/g;}

Note you have to escape the \\p because it's contained in a string now. Tested this on IE11 and it worked (fell back without a fatal parsing error)