I want to make an input where users can write a custom regex in literal notation. I then want to create a RegExp out of that literal notation string.
Something like this:
const literalNotationStr = `/literal/i`;
const regex = makeRegexFromLiteralNotationString(literalNotationStr)
function makeRegexFromLiteralNotationString(str: string): RegExp {
// ... magic code ...
}
Is there a function I'm missing here or is this the kind of thing where you have to parse and build yourself?
You'll have to
(1) grab the flags
(2) slice off the slash delimiters from the beginning and end of the pattern
const literalNotationStr = `/literal/i`;
const regex = makeRegexFromLiteralNotationString(literalNotationStr)
console.log(regex.test('LITERAL'));
function makeRegexFromLiteralNotationString(str){
const [, patternContent, flags] = str.match(/^\/(.+)\/(\w*)$/);
return new RegExp(patternContent, flags);
}But you'll have to make sure the input string has its backslashes properly escaped, eg:
const literalNotationStr = String.raw`/foo\w+/i`;
and not
const literalNotationStr = `/foo\w+/i`;
The flag has to be provided as the second argument. You can e.g. split the literal to get the Regex body and the flag separately and then use it within the Regex constructor.
const literalNotationStr = '/literal/i';
const createRegex = (str) => {
const [, literal, flag] = str.split('/');
return new RegExp(literal, flag);
};
console.log(createRegex(literalNotationStr));
/delimiters? Other sites that do this put the delimiters outside the input to show that they're not needed. The flags could go in a separate input.literal notationstring but what does that mean ? If you have an input box, everything that is typed in that box goes into a variable unchanged. That variable is passed to the RegExp function unchanged. I guess I don't understand.