Closest sum tuple from two arrays

optimised.js

// O(a+b) := O(2n) := O(n)
function optimizedFindClosestSumTupple(arr1, arr2, requiredSum) {
    const map = new Map();
    let minDiff = Number.MAX_VALUE;
    const result = [];
    arr1 = arr1.sort((a, b) => a - b > 0 ? 1 : -1);
    arr2 = arr2.sort((a, b) => a - b > 0 ? 1 : -1);
    for (let l = 0, r = arr2.length - 1; l < arr1.length && r >= 0;) {
        const sum = arr1[l] + arr2[r];
        const diff = Math.abs(sum - requiredSum);
        if (diff < minDiff) {
            minDiff = diff;
        }
        map.set([arr1[l], arr2[r]], diff);
        if (sum > requiredSum) {
            r--;
        } else {
            l++;
        }
    }
    map.forEach((val, key) => {
        if (val === minDiff) {
            result.push(key);
        }
    })
    return result;
}
const arr1 = [4, 3, 7, 5, 1, -10];
const arr2 = [10, 20, 25, 40, 33];
const requiredSum = 16;
const optimizedResult = optimizedFindClosestSumTupple(arr1, arr2, requiredSum);
console.log(optimizedResult);

unoptimised.js

// O(aXb) := O(n^2)
function findClosestSumTupple(arr1, arr2, requiredSum) {
    const map = new Map();
    let minDiff = Number.MAX_VALUE;
    const result = [];
    arr1.forEach(a => {
        arr2.forEach(b => {
            const diff = Math.abs(requiredSum - (a + b));
            map.set([a, b], diff);
            if (diff < minDiff) {
                minDiff = diff;
            }
        })
    })
    map.forEach((val, key) => {
        if (val === minDiff) {
            result.push(key);
        }
    })
    return result;
}

const arr1 = [4, 3, 7, 5, 1, -10];
const arr2 = [10, 20, 25, 40, 33];
const requiredSum = 16;
const result = findClosestSumTupple(arr1, arr2, requiredSum);
console.log(result);