basic java script json child array decoding

Question

I have been teaching myself some basic javascript the last couple of days and playing with google scripting as well as the twitter api and have come a bit unstuck on something that should probably be quite easy!

For sake of easierness of typing so my return from twitter api looks like this

[id:1
connections: "NONE"
],

[id:2
connections: ["following", "followed_by"]
]

What I am trying to do is find out out if the key 'following' exists for user 2, but I am really struggling!

The twitter api docs show an examples json as

[
  {
    "name": "Taylor Singletary",
    "id_str": "819797",
    "id": 819797,
    "connections": [
      "none"
    ],
    "screen_name": "episod"
  },
  {
    "name": "Twitter API",
    "id_str": "6253282",
    "id": 6253282,
    "connections": [
      "following",
      "followed_by"
    ],
    "screen_name": "twitterapi"
  }
]

Can any point me in the correct direction?, how do I find out if following exists?

Thanks

Not sure if I understand, you want to check of the second element in array has the value 'following' in connections array? — juvian
– juvian, Commented Apr 10, 2014 at 17:54
Hi juvian, that is correct, however if it doesnt exist then the array just reads "connections":["followed_by"], is there a way to count the results? — dave
– dave, Commented Apr 10, 2014 at 17:58

phylax · Accepted Answer · 2014-04-10 18:22:34Z

2

connections: ["following", "followed_by"] is an array. To check if an array contains a special value you can use indexOf():

var a = [1, 2, "three", 44];
a.indexOf(1); // 0
a.indexOf(2); // 1
a.indexOf("three"); // 2
a.indexOf(22); // -1

So to check if "following" is in the array:

if (connections.indexOf("following") !== -1) {
  // yeah!
} else {
  // doh!
}

To count the objects in your example which have "following":

var o = [
  {
    "name": "Taylor Singletary",
    "id_str": "819797",
    "id": 819797,
    "connections": [
      "none"
    ],
    "screen_name": "episod"
  },
  {
    "name": "Twitter API",
    "id_str": "6253282",
    "id": 6253282,
    "connections": [
      "following",
      "followed_by"
    ],
  "screen_name": "twitterapi"
  }
];

var withFollowing = o.filter(
  function (i) {
    return i.connections.indexOf("following") !== -1;
  }
);
// filter() returns a new array
// this new array has only the elements for which the function returns true

console.log(withFollowing.lenght);

edited Apr 10, 2014 at 18:22

answered Apr 10, 2014 at 18:13

phylax

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1 Comment

dave Over a year ago

Awesome answer, thanks that really helped, kudos for the range of possibilities as well!

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