class Solution {
    findDifferenceArray(nums) {
        const n = nums.length;
        const differenceArray = new Array(n).fill(0);
        let right = nums.reduce((acc,curr)=>acc+curr, 0)
        let left = 0;
        for(let i = 0; i<nums.length; i++) {
            right-= nums[i]
            differenceArray[i] = Math.abs(left - right);
            left+= nums[i]
        }
        // TODO: Write your code here
        return differenceArray;
    }
}

I think we can just sum all the numbers and then iteratively subtract from right and add to left. The solution is done in two passes instead of three and saves space by not creating additional arrays for left and right. It's less complicated too