Javascript Arrays - Checking two arrays of objects for same contents, ignoring order

user_238030 0
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I have two JavaScript arrays (A and B) that contain objects that I created. I want to check that all the objects in array A are contained in array B, but not necessarily in the same order.

What is the best way to do this?

Edit:

They are all actual objects, not primitives, so I will need to compare their contents and structure as well (maybe using something like JSON.stringify).

I want to do this because I'm learning Test-Driven Development, and I want to test functions that return lists of objects. I need to test whether the returned lists have the expected objects in them or not (order doesn't matter in this case).

compare arrays comparison javascript
5 Answers

With ES6 you could use every and some (and length).

let A = [1, 2, 3];
let B = [2, 3, 1];

// all objects in A are contained in B (A ⊆ B)
// you can compare a <-> b however you'd like (here just `a === b`)
let AsubB = A.every(a => B.some(b => a === b));

// A and B are the same length
let sameLength = A.length === B.length;

// their contents are as equal as previously tested:
let equal = AsubB && sameLength;
user_2161290

Simple & Elegant

function isEqual(arr1, arr2) {
    if (arr1.length !== arr2.length)
        return false;
    return arr1.every(x => arr2.includes(x));
}

If duplication is important, use this

function isEqual(arr1, arr2) {
    if (arr1.length !== arr2.length)
        return false;
    arr1.sort();
    arr2.sort();
    for (var i = 0; i < arr1.length; i++) {
        if (arr1[i] !== arr2[i])
            return false;
    }
    return true;
}
user_180292200
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