tape-equilibrium.js

function solution(A) {        
    var p, idx,
        leftSum = 0,
        rightSum = 0,
        totalSum = A.reduce(function(pv, cv) { return pv + cv; }, 0),
        lastMin,
        currentMin,
        N = A.length;
    
    if (N === 2) {
      return Math.abs(A[0] - A[1]);
    }
    
    if (N === 1) {
      return Math.abs(A[0]);
    }
    
    lastMin = Math.abs(totalSum - A[0] - A[0]);
    
    for (p = 1; p <= N - 1; p++) {
        leftSum += A[p - 1];
        rightSum = totalSum - leftSum;
        currentMin = Math.abs(leftSum - rightSum);
        lastMin = (currentMin < lastMin) ? currentMin : lastMin;
    }
    
    return lastMin;   
}