Count all K-Sum Paths in a Binary Tree using JavaScript

class T_Node {
    constructor(value = 0, left = null, right = null) {
        this.value = value;
        this.left = left;
        this.right = right;
    }
}

function count_Paths_Fun(root, k) {
    let pathCount = 0;
    let prefixSums = { '0': 1 };

    function dfs(node, currentSum) {
        if (!node) return;

   // Update the current sum with the value of the current node
        currentSum += node.value;
        let oldSum = currentSum - k;
        pathCount += (prefixSums[oldSum] || 0);
        prefixSums[currentSum] = 
                    (prefixSums[currentSum] || 0) + 1;
        dfs(node.left, currentSum);
        dfs(node.right, currentSum);
        prefixSums[currentSum] -= 1;
    }

    dfs(root, 0);
    return pathCount;
}

// Constructing the tree as shown in the diagram
const root = new T_Node(10);
root.left = new T_Node(5);
root.right = new T_Node(-3);
root.left.left = new T_Node(3);
root.left.right = new T_Node(2);
root.right.right = new T_Node(11);
root.left.left.left = new T_Node(3);
root.left.left.right = new T_Node(-2);
root.left.right.right = new T_Node(1);

const k = 8;
const result = count_Paths_Fun(root, k);
console.log(`Number of paths that sum to ${k}: ${result}`);