routes/post.js
function parseJSON(input, callback) {
  var error
  var result
  try {
    result = JSON.parse(input) }
  catch (e) {
    error = e }
  callback(error, result) }
function parseJSON(input, callback) {
  var error
  var result
  try {
    result = JSON.parse(input) }
  catch (e) {
    error = e }
  callback(error, result) }
JSON.parse, wrapped to take an errback.