overleaf/services/real-time/app/js/SafeJsonParse.js

const Settings = require('settings-sharelatex')
const { DataTooLargeToParseError } = require('./Errors')

module.exports = {
  parse(data, callback) {
    if (data.length > Settings.maxUpdateSize) {
      return callback(new DataTooLargeToParseError(data))
    }
    let parsed
    try {
      parsed = JSON.parse(data)
    } catch (e) {
      return callback(e)
    }
    callback(null, parsed)
  }
}