check and compare 2 arrays

Question

function calWinner(arr) { //winning combination const winningIds = [ [0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6], ] for (let i = 0; i < winningIds.length; i++) { calculate(arr, winningIds[i]) } } function calculate(sup, sub) { sup.sort() sub.sort() let i = 0 let j = 0 for (i, j; i < sup.length && j < sub.length;) { if (sup[i] < sub[j]) { ++i } else if (sup[i] == sub[j]) { ++i, ++j } else { return false } } return j == sub.length; } calWinner([1, 3, 7, 4])

I'm trying to write a function that takes an array, and check if it has every element in a nested array in an object inside of the function.

I've added a function I found from this post, but not sure why i am getting undefined instead of true.

In the old days of Yore I had been studiyng Pascal, and there there was an excellent relational operator ‘IN’. One could use it to determine whether one array is a subset of another one. If Pascal could do it, modern languages should have similar features too. — wintermute
– wintermute, Commented Feb 12, 2018 at 4:27
@wintermute you are right - using a modern search engine reveals the presence of array.includes in JavaScript — Adnan S
– Adnan S, Commented Feb 12, 2018 at 4:30
thanks @diogenesgg, i thought it was, as the nested calculate function returns either true or false. could you tell me how calWinner can return something? — bom
– bom, Commented Feb 12, 2018 at 4:39

diogenesgg · Accepted Answer · 2018-02-12 04:49:16Z

Assuming you want to return true if any array from winningIds is inside arr, this is the code:

function calWinner(arr) { //winning combination const winningIds = [ [0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6], ] var containsWinner = false; for (let i = 0; i < winningIds.length && !containsWinner; i++) { containsWinner = calculate(arr, winningIds[i]) } return containsWinner; } function calculate(sup, sub) { sup.sort() sub.sort() for (var i = 0; i < sub.length; i++) { if (sup.indexOf(sub[i]) == -1) { return false; } } return true; } calWinner([1, 3, 7, 4]);

To make it stop at the the first winningId it finds; After checking that [1, 4, 7] is inside arr, containsWinner becomes true, and the loop stops;
thanks so much! totally missed the part that containsWinner was assigned to the result of calculate()!

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