I _think_ this issue is because regex lookbehind is not supported across all browsers, per https://stackoverflow.com/questions/51568821/works-in-chrome-but-breaks-in-safari-invalid-regular-expression-invalid-group .
I think this issue is because regex lookbehind is not supported across all browsers, per https://stackoverflow.com/questions/51568821/works-in-chrome-but-breaks-in-safari-invalid-regular-expression-invalid-group .