Kadane algorithm In computer science, the maximum subarray problem is the task of finding the contiguous subarray within a one-dimensional array of numbers which has the largest sum. For example, for the sequence of values −2, 1, −3, 4, −1, 2, 1, −5, 4. The contiguous subarray with the largest sum is 4, −1, 2, 1, with sum 6.

kadane.js

var a = [ -2, 1, -3, 4, -1, 2, 1, -5, 4 ],
    now = 0,
    prev = 0;

for ( var i = 0; i < a.length; i++ ) {
    prev = Math.max( 0, prev + a[ i ] );
    now = Math.max( prev, now );
}

console.log( now ); // 6