An ugly but effective way of serializing and parsing Javascript bigints.

ugly-bigint-patch.js

/* 
 * This uggly patch around the built-in JSON.stringify and JSON.parse exists mainly to bridge the gap between JS number 
 * which can only safely represent integers up to 2^53 - 1 and systems that support larger boundaries.
 */

BigInt.prototype.toJSON = function() {
  return `$bigint:${this.toString()}`;
}

function bigIntReviver(_k, value, context) {
  const rawValue = context?.source;
  if(typeof rawValue === 'string' 
     && rawValue.match(/^\-?\d+$/g)) {
    const maybeBig = BigInt(rawValue);
    if(maybeBig < Number.MIN_SAFE_INTEGER
        || maybeBig > Number.MAX_SAFE_INTEGER) {
      return maybeBig;
    }
  }
  return value;
}

const origJsonStringify = JSON.stringify;

JSON.stringify = function(value, replacer, space) {
  const formatted = origJsonStringify(value, replacer, space);
  return formatted.replaceAll(/"\$bigint:(\-?\d+)"/g, '$1');
}

const origJsonParse = JSON.parse;

JSON.parse = function(value, reviver) {
  if(typeof reviver === 'function') {
    return origJsonParse(value, reviver);
  }
  return origJsonParse(value, bigIntReviver);
}