Sum of Root To Leaf Binary Numbers.js

// Runtime: 113 ms (Top 42.26%) | Memory: 44.9 MB (Top 34.73%)
var sumRootToLeaf = function(root) {

    let sum = 0;

    const getSum = (root, currStr) => {
        if(!root) {
            return;
        }

        if(!root.left && !root.right) {
            sum = sum + parseInt(currStr + root.val, 2);
        }

        getSum(root.left, '' + currStr + root.val);
        getSum(root.right, '' + currStr + root.val);
    }

    getSum(root, '');

    return sum;
};