js-tokens
The tiny, regex powered, lenient, almost spec-compliant JavaScript tokenizer that never fails.
const jsTokens = require("js-tokens");
const jsString = 'JSON.stringify({k:3.14**2}, null /*replacer*/, "\\t")';
Array.from(jsTokens(jsString), (token) => token.value).join("|");
// JSON|.|stringify|(|{|k|:|3.14|**|2|}|,| |null| |/*replacer*/|,| |"\t"|)