Get object of array in array in JavaScript

Question

I'm looking for a way of incrementing a number, therefore I need to find the object which is identified by an id first. More specifically, I want to increment the votes of a specific object.

The data structure looks like this:

const polls = [
  {
    id: "9efd91dc-b762-11e8-bfb8-c471feb11e42",
    owner: "d926e95c-b696-11e8-8a0f-c471feb11e42",
    question: "How are you? 1536849484",
    tenement: "0cec2fc2-b697-11e8-8a0f-c471feb11e42",
    participation: 0,
    poll_answer_options: [
      {
        id: "9efd9b32-b762-11e8-bfb8-c471feb11e42",
        owner: "d926e95c-b696-11e8-8a0f-c471feb11e42",
        answer_text: "Not so Fine",
        votes: 0
      },
      {
        id: "9efd97b8-b762-11e8-bfb8-c471feb11e42",
        owner: "d926e95c-b696-11e8-8a0f-c471feb11e42",
        answer_text: "Fine",
        votes: 0 // -> want to increment
      }
    ]
  },
  {
    id: "13b43584-b697-11e8-b2c2-c471feb11e42",
    owner: "d926e95c-b696-11e8-8a0f-c471feb11e42",
    question: "How are you? 1536762062",
    tenement: "0cec2fc2-b697-11e8-8a0f-c471feb11e42",
    participation: 1,
    poll_answer_options: [
      {
        id: "13b43f66-b697-11e8-b2c2-c471feb11e42",
        owner: "d926e95c-b696-11e8-8a0f-c471feb11e42",
        answer_text: "Not so Fine",
        votes: 1
      },
      {
        id: "13b43bd8-b697-11e8-b2c2-c471feb11e42",
        owner: "d926e95c-b696-11e8-8a0f-c471feb11e42",
        answer_text: "Fine",
        votes: 0
      }
    ]
  }
];

I tried with the JavaScript find method like shown below, but this doesn't work.

let pollAnswerOptions = polls.find(
    poll => poll.poll_answer_options.id === "9efd97b8-b762-11e8-bfb8-c471feb11e42"
  );

Well both answers in each poll seem to have the same ID, so it's not clear how it's logically possible to target one of them. — Mitya
– Mitya, Commented Sep 13, 2018 at 18:15

Nina Scholz · Accepted Answer · 2018-09-13 18:16:53Z

You need a nested approach and if you have only one id to find, you could use a short circuit to prevent more iterating.

const
    polls = [{ id: "9efd91dc-b762-11e8-bfb8-c471feb11e42", owner: "d926e95c-b696-11e8-8a0f-c471feb11e42", question: "How are you? 1536849484", tenement: "0cec2fc2-b697-11e8-8a0f-c471feb11e42", participation: 0, poll_answer_options: [{ id: "9efd9b32-b762-11e8-bfb8-c471feb11e42", owner: "d926e95c-b696-11e8-8a0f-c471feb11e42", answer_text: "Not so Fine", votes: 0 }, { id: "9efd97b8-b762-11e8-bfb8-c471feb11e42", owner: "d926e95c-b696-11e8-8a0f-c471feb11e42", answer_text: "Fine", votes: 0 }] }, { id: "13b43584-b697-11e8-b2c2-c471feb11e42", owner: "d926e95c-b696-11e8-8a0f-c471feb11e42", question: "How are you? 1536762062", tenement: "0cec2fc2-b697-11e8-8a0f-c471feb11e42", participation: 1, poll_answer_options: [{ id: "13b43f66-b697-11e8-b2c2-c471feb11e42", owner: "d926e95c-b696-11e8-8a0f-c471feb11e42", answer_text: "Not so Fine", votes: 1 }, { id: "13b43bd8-b697-11e8-b2c2-c471feb11e42", owner: "d926e95c-b696-11e8-8a0f-c471feb11e42", answer_text: "Fine", votes: 0 }] }],
    id = '9efd97b8-b762-11e8-bfb8-c471feb11e42';

polls.some(o => o.poll_answer_options.some(option => {
    if (option.id === id) {
        ++option.votes;
        return true;
    }
}));

console.log(polls);

.as-console-wrapper { max-height: 100% !important; top: 0; }

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