Some error in solutions

[BranDanny]

// Challenge 7
const intersection = (arrays) => {
return arrays.reduce((acc, curr) => {
return curr.filter(el => acc.includes(el));
});
};

// console.log(intersection([5, 10, 15, 20], [15, 88, 1, 5, 7], [1, 10, 15, 5, 20]));
Uncaught TypeError: curr.filter is not a function

Should be:
const intersection = (...arrays) => {
return arrays.reduce((acc, curr) => {
return curr.filter(el => acc.includes(el));
});
};

and similar error downside :)

[JoSaGuDu]

Yep, same error spotted here. An alternative solution is to rewrite the test statement:

Instead of :

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

test with:

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

Final code would be:

// Challenge 7
function intersection(arrays) {
  return arrays.reduce((acc, curr) => {
    return curr.filter(el => acc.includes(el));
 });
}

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

Same for challenge 8

[daneelf]

Actually, challenge 7 should be:

function intersection(...arrays) {
  return arrays.reduce((acc, curr) => {
    return curr.filter(el => acc.includes(el));
 });
}