Invalid regular expression: invalid group specifier name - a regex expression that breaks on any iOS device

let addCommas = (number) => {
        let [head, ...rest] = number.toString().split('.');
        rest.length === 0 ? rest = ['00'] : rest;
        return head.toString().replace(/\B(?<!\.\d*)(?=(\d{3})+(?!\d))/g, ",") + '.' + rest;
    }

the regex part breaks my code on any ios device. even on google chrome.

for the life of me, I couldn't understand why.

any thoughts and or ways I could go around this?