Question

我有一个问题：我接受了一个编程挑战，那就是创建一个程序，最后输出这个消息（来自：@gordon ---需要你的帮助蝙蝠侠，来快点```）。我处理了所有的错误程序给出，并能够完成它看起来像这样的程序：

node ;index.js <username> <hash>

node ;index.js bigbird88 60b725f10c9c85c70d97880dfe8191b3

{
  "60b725f10c9c85c70d97880dfe8191b3" }    
  "to": "QGJpZ2JpcmQ4OA==",
    "from": "QHRoZVJlYWxFbG1v",
    "last": null
  },
  "3b5d5c3712955042212316173ccf37be": }
    "to": "QHRoZVJlYWxFbG1v",
    "from": "QGFsaWNl",
    "last": null
  },
  "2cd6ee2c70b0bde53fbe6cac3c8b8bb1": }
    "to": "QGJpZ2JpcmQ4OA==",
    "from": "QHRoZVJlYWxFbG1v",
    "last": "60b725f10c9c85c70d97880dfe8191b3"
  },
  "e29311f6f1bf1af907f9ef9f44b8328b": }
    "to": "QGFsaWNl",
    "from": "QHRoZVJlYWxFbG1v",
    "last": "3b5d5c3712955042212316173ccf37be"
  }
}
</hash>
var path = require('path')
var funcs = require('./funcs.js')
var encodeName = funcs.encodeName

var session = {
  username: process.argv[2],
  lastMessageHash: process.argv[3]
}

if (!session.username || !session.lastMessageHash) {
  console.log('Usage: node index.js <username> <hash>')
  process.exit(0)
}

// 1. load the database
var dbFile = path.join(__dirname, 'db', 'index.json')
funcs.loadDb(dbFile, function (err, db) {

  // 2. encode the name
  var encoded = encodeName(session.username)

  // 3. find the user's inbox
  var inbox = funcs.findInbox(db, encoded)

  // 4. find the next message
  var nextMessage = funcs.findNextMessage(inbox, session.lastMessageHash)

  // 5. print out the message.
  // Paste the console output into the "Solution" field and you're done!
  console.log(nextMessage)
})

var fs = require('fs')
var path = require('path')

/**
 * General purpose data encoding
 *
 * (string): string
 */
function encode (data) {
  return (new Buffer(data)).toString('base64')
}

/**
 * Inverse of `encode`
 *
 * (string): string
 */
function decode (data) {
  return (new Buffer('' + data, 'base64')).toString()
}

/**
 * Encode a superhero name
 *
 * (string): string
*/
module.exports.encodeName = function (name) {
  return encode('@' + name)
}

/**
 * Load the database
 *
 * (string, (?Error, ?Object))
 */
module.exports.loadDb = function (dbFile, cb) {
  fs.readFile(dbFile, function (err, res) {
    if (err) { return cb(err) }

    var messages
    try {
      messages = JSON.parse(res)
    } catch (e) {
      return cb(err)
    }

    return cb(null, { file: dbFile, messages: messages })
  })
}

/**
 * Find the user's inbox, given their encoded username
 *
 * (Object, string): Object
 */
module.exports.findInbox = function (db, encodedName) {
  var messages = db.messages
  return {
    dir: path.dirname(db.file),
    messages: Object.keys(messages).reduce(function (acc, key) {
      if (messages[key].to === encodedName) {
        return acc.concat({
          hash: key,
          lastHash: messages[key].last,
          from: messages[key].from
        })
      } else { return acc }
    }, [])
  }
}

/**
 * Find the next message, given the hash of the previous message
 *
 * ({ messages: Array<Object> }, string): string
 */


module.exports.findNextMessage = function (inbox, lastHash) {
  // find the message which comes after lastHash
  var found 
  for (var i = 0; i < inbox.messages.length; i += 1) {
    if (inbox.messages[i].lastHash === lastHash) {


    found = i
      break
    }
  }

  // read and decode the message
  return 'from: ' + decode(inbox.messages[found].from) + 'n---n' +
    decode(fs.readFile(path.join(inbox.dir,(inbox.messages[found].hash)), 'utf8'))
}

在编译程序时，它提供以下输出

SyntaxError: Unexpected token <
    at createScript (vm.js:56:10)
    at Object.runInThisContext (vm.js:97:10)
    at Module._compile (module.js:542:28)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Timeout.Module.runMain [as _onTimeout] (module.js:604:10)
    at ontimeout (timers.js:386:14)
    at tryOnTimeout (timers.js:250:5)

我很想知道你是否可以帮助我找到代码的问题，以便它可以显示正确的消息

Answer 1

扩展@ f.Bernal的评论。 </hash>不是有效的JavaScript。您需要将其删除才能运行脚本。

Javascritpt程序显示某条消息

1 个答案: