const sumPoint = (arr) => { const len = arr.length; let sum = 0; let leftsum = 0; for (let i = 0; i < len; i++) { sum += arr[i]; } for (let j = 0; j < len; j++) { sum -= arr[j]; if (leftsum === sum) { return j; } leftsum += arr[j]; } return false; } const arr = [1,2,2,9,3,2]; console.log(sumPoint(arr));