javascript - Compare arrays of objects independent of the order - Stack Overflow

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I have 2 arrays of objects and I have to pare them, but the order of the objects DOES NOT matter. I can't sort them because I won't have their keys' names because the functions must be generic. The only information that I'll have about the array is that both array's objects have the same amount of keys and those keys have the same name. So the array1 must contain the same objects as the array2.

var array1 = [{"key1":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
var array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];

In the example, array1 must be equal array2. I tryed to use the chai .eql() method but it didn't work.

I have 2 arrays of objects and I have to pare them, but the order of the objects DOES NOT matter. I can't sort them because I won't have their keys' names because the functions must be generic. The only information that I'll have about the array is that both array's objects have the same amount of keys and those keys have the same name. So the array1 must contain the same objects as the array2.

var array1 = [{"key1":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
var array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];

In the example, array1 must be equal array2. I tryed to use the chai .eql() method but it didn't work.

• javascript
• arrays
• json
• chai
• unordered

Share Improve this question Follow edited Oct 31, 2017 at 17:43 mplungjan 178k2828 gold badges182182 silver badges240240 bronze badges asked Oct 31, 2017 at 17:34 Brian BatistaBrian Batista 6711 silver badge66 bronze badges 2

• What does "pare them" mean? Do you just need to know if they are the same or not? A boolean response? – Alec Fenichel Commented Oct 31, 2017 at 17:41
• Are all values string type ? – komron Commented Oct 31, 2017 at 17:44

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3 Answers 3

Sorted by: Reset to default 7

The following solution:

• will verify that the arrays have an equal number of elements
• does not impose restrictions on keys (as to not contain a certain delimiter)
• requires both keys and (string) values to be the same
• has a time plexity of O(nlogn) (instead of O(n²) as some other solutions here)

function equalArrays(a, b) {
    if (a.length !== b.length) return false;
    const ser = o => JSON.stringify(Object.keys(o).sort().map( k => [k, o[k]] ));
    a = new Set(a.map(ser));
    return b.every( o => a.has(ser(o)) );
}

// Example
var array1 = [{"key1":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
var array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];
console.log(equalArrays(array1, array2)); // true
// Example with different key name
var array1 = [{"key0":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
var array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];
console.log(equalArrays(array1, array2)); // false

You can array#join each value of the object on an separator and then generate a new array of string and then pare each values using array#every and array#includes

var array1 = [{"key1":"Banana", "key2":"Yammy"}, {"key1":"Broccoli", "key2":"Ew"}];
    array2 = [{"key1":"Broccoli", "key2":"Ew"}, {"key1":"Banana", "key2":"Yammy"}];
    values = (o) => Object.keys(o).sort().map(k => o[k]).join('|'),
    mapped1 = array1.map(o => values(o)),
    mapped2 = array2.map(o => values(o));

var res = mapped1.every(v => mapped2.includes(v));

console.log(res);

You can do something like following:

For each object in each array you can calc its representation:

arr1.forEach( (obj) => {
    obj.representation = '';
    for (let key of Object.keys(obj)) {
      obj.representation += obj[key];
    }
}

Same for arr2

now you can sort both arrays by representation for example and then pare.

To sort do the following:

arr1.sort( (a,b) => { return a.representation > b.representation } );
arr2.sort( (a,b) => { return a.representation > b.representation } );

After sorting you can pare both arrays

let equal = arr1.every( (el, i) => arr2[i]===el );

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