Codility #8-TapeEquilibrium

function solution(A) {

let sumAll = A.reduce((accu, curr) => accu + curr, 0); // sum of the array

let minDiff = Number.MAX_VALUE;

for (let i = 0, sumPart = 0, diff, n = A.length - 1; i < n; i++) {

sumPart += A[i];

// |sum(0~P-1) - sum(P~N-1)| equals to |2*sum(0~P-1) - sum(0~N-1)|

diff = Math.abs(sumPart * 2 - sumAll);

if (diff < minDiff) {

minDiff = diff;

}

}

return minDiff;

}