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I have a function designed to sort / order / uniqify a given array.

Here is some of the code: Bubble Sort - 

function sort(postsCollection, type, direction){
    let target = postsCollection[0][type];
    let swapp = false,
        n = postsCollection[0].length - 1,
        x = postsCollection[0];
    do {
        swapp = false;
        for(let i = 0; i < n; i++){
            if(x[i][type] < x[i+1][type]){
                x[i+1] = x[i];
                swapp = true;
            }
        }
        n--;
    } while (swapp);
    return x;
}

These exist in module.exports: 

    orderPostsCollection(postsCollection, sortType, direction, callback){
    // Unique Array Creater
    let uniq = a => [...new Set(a)];

    if(!sortType && !direction){
        callback([...new Set(postsCollection)]);
    }

    if(sortType) {
        callback(sort([...new Set(postsCollection)], sortType, direction));
    }else if(direction){
        callback(sort([...new Set(postsCollection)], false, direction));
    }
},
uniqify(postsCollection, callback){
    console.log([...new Set(postsCollection)]);
    callback([...new Set(postsCollection)]);
}

it should make the data array unique. But it isn't..

Here is a sample:

{"posts":[{"author":"Rylee Paul","authorId":9,"id":1,"likes":960,"popularity":0.13,"reads":50361,"tags":["tech","health"]},{"author":"Zackery Turner","authorId":12,"id":2,"likes":469,"popularity":0.68,"reads":90406,"tags":["startups","tech","history"]},{"author":"Zackery Turner","authorId":12,"id":2,"likes":469,"popularity":0.68,"reads":90406,"tags":["startups","tech","history"]},{"author":"Zackery Turner","authorId":12,"id":2,"likes":469,"popularity":0.68,"reads":90406,"tags":["startups","tech","history"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Elisha Friedman","authorId":8,"id":13,"likes":230,"popularity":0.31,"reads":64058,"tags":["design","tech"]},{"author":"Adalyn Blevins","authorId":11,"id":37,"likes":107,"popularity":0.55,"reads":35946,"tags":["tech","health","history"]},{"author":"Adalyn Blevins","authorId":11,"id":37,"likes":107,"popularity":0.55,"reads":35946,"tags":["tech","health","history"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Jon Abbott","authorId":4,"id":46,"likes":89,"popularity":0.96,"reads":79298,"tags":["culture","tech"]},{"author":"Bryson Bowers","authorId":6,"id":85,"likes":25,"popularity":0.18,"reads":16861,"tags":["tech"]},{"author":"Bryson Bowers","authorId":6,"id":85,"likes":25,"popularity":0.18,"reads":16861,"tags":["tech"]},{"author":"Bryson Bowers","authorId":6,"id":85,"likes":25,"popularity":0.18,"reads":16861,"tags":["tech"]},{"author":"Bryson Bowers","authorId":6,"id":85,"likes":25,"popularity":0.18,"reads":16861,"tags":["tech"]},{"author":"Bryson Bowers","authorId":6,"id":85,"likes":25,"popularity":0.18,"reads":16861,"tags":["tech"]}]}

why is this array is not made unique? what gives the above result?

SuleymanSah
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LiveBacteria
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1 Answers1

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You're assuming [...new Set(data)] will filter out duplicate values – which is basically correct – but: Sets only filter out duplicates of primitive values (strings, numbers, booleans, etc.). Objects are not considered equal to each other even if they have the exact same content✝.

You could instead call your own uniqueFilter(postsCollection) function instead of using [...new Set(postsCollection)] that does filter objects based on the sameness of their content (see here for some examples).

✝ Objects are only considered "equal" to each other when they're literally references to the same object. e.g.

const a = {};
a === {}; // false

const b = a;
a === b; // true (because `b` is literally pointing to the exact same object as `a`)

Think of every object you make as having a secret key that always makes it unique regardless of its content.

SamVK
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