JavaScript. How to Compare Input Arrays

Question

I\'m stuck with this problem for 3 days now... Someone please help me.

Challenge 5
Construct a function intersection

Answer 1

You could reduce the array by filtering with just checking if the other array contains the value.

This works for arrays with unique values.

Array#reduce:

If no initialValue is provided, then accumulator will be equal to the first value in the array, and currentValue will be equal to the second.

The callback

a.filter(v => b.includes(v))

filters array a. If the array b includes the value of a, then this value v is included in the accumulator for the next iteration or as final result.

     accumulator            currentValue           new accumulator
          a                       b                    result
--------------------    --------------------    --------------------
[     5, 10, 15, 20]    [15, 88,  1,  5,  7]    [             5, 15]
[             5, 15]    [ 1, 10, 15,  5, 20]    [             5, 15]

function intersection(arrayOfArrays) {
    return arrayOfArrays.reduce((a, b) => a.filter(v => b.includes(v)));
}

console.log(intersection([[5, 10, 15, 20], [15, 88, 1, 5, 7], [1, 10, 15, 5, 20]]));