Javascript数组无法作为数组访问

Question

I'm working with the twitter API and I'm hitting a really confusing issue.

I have the following script:

const Twitter = require('twitter-api-stream')
const twitterCredentials = require('./credentials').twitter

const twitterApi = new Twitter(twitterCredentials.consumerKey, twitterCredentials.consumerSecret, function(){
    console.log(arguments)
})

twitterApi.getUsersTweets('everycolorbot', 1, twitterCredentials.accessToken, twitterCredentials.accessTokenSecret, (error, result) => {
    if (error) {
        console.error(error)
    }
    if (result) {
        console.log(result) // outputs an array of json objects
        console.log(result.length) //outputs 3506 for some reason (it's only an array of 1)
        console.log(result[0]) // outputs a opening bracket ('[')
        console.log(result[0].text) // outputs undefined
    }
})

Which is calling the following function to interact with twitter:

TwitterApi.prototype.getUsersTweets = function (screenName, statusCount, userAccessToken, userRefreshToken,cb ) {
    var count = statusCount || 10;
    var screenName = screenName || "";

    _oauth.get(
        "https://api.twitter.com/1.1/statuses/user_timeline.json?count=" + count + "&screen_name=" + screenName
        , userAccessToken
        , userRefreshToken
        , cb
    );
};

It seems like I'm getting the result I want. When I log the result itself I get the following output:

[
  {
    "created_at": "Thu Sep 01 13:31:23 +0000 2016",
    "id": 771339671632838656,
    "id_str": "771339671632838656",
    "text": "0xe07732",
    "truncated": false,
    ...
  }
]

Which is great, an array of the tweets limited to 1 tweet.

The problem I'm running into is when I try to access this array.

console.log(result.length) //outputs 3506 for some reason (it's only an array of 1)
console.log(result[0]) // outputs a opening bracket ('[')
console.log(result[0].text) // outputs undefined

I read back through the api docs for the user_timeline but unless I'm completely missing it I'm not seeing any mention of special output.

Any ideas?

Update

Thanks @nicematt for pointing out that answer.

Just to elaborate on the solution, I updated my code to this and now I'm getting the result I want:

if (result) {
    let tweet = JSON.parse(result)[0] // parses the json and returns the first index
    console.log(tweet.text) // outputs '0xe07732'
}

Thanks for the help!

Answer 1

Result is a String and you're indexing it ( result[0] (whereas 0 is converted to a string), is almost identical to result.charAt(0) though), this is why result[0] is equal to "[" –because it's the first character specified in. You forgot to parse the result as JSON data.

JSON.parse(result).length // probably 1

And result.text is undefined since result (a string) is like an Object (but isn't instanceof) and allow lookups and getters to happen in itself.

I'd show the difference between str[0] and str.charAt(0) , too:

str[0] // same as str['0'], but a getter. 0 converts to
       // string (because every key of an object
       // is string in ECMAScript)

str.charAt(0) // get/lookup String#charAt, call it
              // without new `this` context and with arguments list: 0