Polyfill for JSON.stringify

json_stringify_polyfill.js

function stringify(data) {
if (data === undefined)
  return undefined
if (data === null)
  return 'null'
if (data.toString() === "NaN")
  return 'null'
if (data === Infinity)
  return 'null'
if (data.constructor === String)
  return '"' + data.replace(/"/g, '\\"') + '"'
if (data.constructor === Number)
  return String(data)
if (data.constructor === Boolean)
  return data ? 'true' : 'false'
if (data.constructor === Array)
  return '[' + data.reduce((acc, v) => {
    if (v === undefined || v === NaN || v === Infinity)
      return [...acc, 'null']
    else
      return [...acc, stringify(v)]
   }, []).join(',') + ']'

if (data.constructor === Object)
  return '{' + Object.keys(data).reduce((acc, k) => {
    if (data[k] === undefined)
      return acc
    else
      return [...acc, stringify(k) + ':' + stringify(data[k])]
    }, []).join(',') + '}'

  return '{}'
}