Same JSON ojbects in array when receiving differnt array elements

Question

In my NodeJS app i get an JSON object within jade (which works fine). Here in i tried to collect(srcTweets) only the relevant data and return this in a new JSON object(stgTweets). Which i use for Dynamic Table use.

Here fore i use the following scrip:

    var srcTweets = [];
    var srcTweets = !{JSON.stringify(tweets)};
    var aantalSrcTweets = srcTweets.length;

    //Loop throug all tweets and collect all relevant elementen from srcTweet:
    var stgTweet = {}
    var stgTweets = [];
    console.info('----------START LOOP--------------------');
    for(var i = 0; i < aantalSrcTweets; i++){
        console.info(i);

        stgTweet.Id = srcTweets[i]._id;
        stgTweet.userId = srcTweets[i].user.id;
        stgTweet.userFollowerCount = srcTweets[i].user.followers_count;
        stgTweet.userFriendCount = srcTweets[i].user.friends_count;
        stgTweet.userFavouritesCount = srcTweets[i].user.favourites_count;
        stgTweet.text = srcTweets[i].text;
        stgTweet.coordinates = srcTweets[i].coordinates;
        stgTweet.userLocation = srcTweets[i].user.location;

        stgTweets[i] = stgTweet;

        console.info(stgTweets[i]);
        console.info(i);
    }
    console.info('----------END LOOP--------------------');

    //here i get the same items
    console.info(stgTweets[0]);
    console.info(stgTweets[1]);

When i print different index numbers of the array "stgTweet[0] and stgTweet[1]" the same data is showed. I tried to figure it out by logging the elements in the for loop , but that looks fine. And i realy don't know where to look futher.

How do i fill the array with different objects in stead of the same object, what happens in the script above.

Here is an example of the srcTweets:

[
   Object   {
      _id="56e19eb1ac5e621e0797c423",
      truncated=false,
      text="@Model_Symphony nu ja,
      s... prima Energiequelle...",
      more...
   },
   Object   {
      _id="56e1a73eac5e621e0797c424",
      truncated=false,
      text="Vandaag aangekondigd doo...",
      more...
   },
   Object   {
      _id="56e1a7b4ac5e621e0797c425",
      truncated=false,
      text="Mooi bedrijfsbezoek aan ...",
      more...
    }
]

mscdex · Accepted Answer · 2016-03-26 15:46:51Z

1

The reason is because you're reusing the same object for every element in the array and objects are assigned by reference in Javascript, so stgTweets[0] === stgTweets[1].

What you could do instead is move your stgTweet declaration inside the loop (or just re-assign the value directly as shown below) so that a new object is created for each array element:

var stgTweets = new Array(aantalSrcTweets);
for (var i = 0; i < aantalSrcTweets; i++){
  stgTweets[i] = {
    Id: srcTweets[i]._id,
    userId: srcTweets[i].user.id,
    userFollowerCount: srcTweets[i].user.followers_count,
    userFriendCount: srcTweets[i].user.friends_count,
    userFavouritesCount: srcTweets[i].user.favourites_count,
    text: srcTweets[i].text,
    coordinates: srcTweets[i].coordinates,
    userLocation: srcTweets[i].user.location
  };
}

edited Mar 26, 2016 at 15:46

answered Mar 26, 2016 at 15:41

mscdex

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1 Comment

Erik hoeven Over a year ago

Many thanks!! Your realy smart.. I can't accept the answer within 4 minutes. So i do that about 30 minutes if that is alread for you :-)

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