JSON/JSON5 BigInt Replacer and Reviver

bigint-replacer.js

function bigIntReplacer(key, value) {
  if (typeof value === 'bigint') {
    return `${value}n`
  }

  return value
}

bigint-reviver.js

function bigIntReviver(name, value) {
  const bigIntRegExp = /^([-+]?\d+)n$/
  
  if (typeof value === 'string') {
    const match = bigIntRegExp.exec(value)
    if (match != null) {
      return BigInt(match[1])
    }
  }

  return value
}