A step-by-step guide on extracting multiple data entries from JSON that correspond to an array of IDs

Within my JavaScript code, I am working with a JSON dataset containing posts, each with a unique post_id. I also have an array of specific post_ids that I want to use to extract certain posts from the main dataset.

const dataset = [
     {post_id: 1, title: 'First Post'},
     {post_id: 2, title: 'Second Post'},
     {post_id: 3, title: 'Third Post'},
];

Next, I have an array specifying the posts I want to retrieve:

const posts_to_get = [0,3];

How can I properly parse the dataset to extract posts with id = 0 and id = 3?

Given that my array may contain numerous IDs, I understand that I will need to iterate through it. While loops may be an option, I'm hesitant about their efficiency.

Note: Currently, I am setting up a 'mock backend' for a frontend application. In the long run, I plan to implement a more efficient method for fetching posts. However, for now, I am working with this single JSON dataset.

Appreciate the assistance!

javascriptjsonecmascript-6

Answer №1

Is this example similar to what you are looking for?

const data = [
     {id: 1, name: 'First Item'},
     {id: 2, name: 'Second Item'},
     {id: 3, name: 'Third Item'},
];
const items_to_select = [1,3];
var selection = data.filter(item=>items_to_select.includes(item.id))
console.log(selection)

Answer №2

When dealing with a large dataset, consider converting the array to an object before attempting to read it.

const transformedData = dataset.reduce((obj, current) => {
    obj[current.post_id] = current;
    return obj;
}, {});

By converting the array to an object, look ups will be faster and constant time. Just remember to convert the post_id you're searching for to a string:

const idsToFind = [1, 3];
console.log(idsToFind.map(id => transformedData[id.toString()]));

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