Sum tree with data stack (no call stack). Breadth first traversal

sum-tree.es6

function sumTree (tree) {
    var sum = tree.value;
    var root = tree;
    var stack = [root.next];
    
    while(stack.length) {
        sum = stack.pop().reduce((sum, root) => {
            stack.push(root.next);
            return sum + root.value;
        }, sum);
    }
    
    return sum;
}

var tree = {
    "value": 5,
    "next": [
        {
            "value": 3,
            "next": [
                {
                    "value": 3,
                    "next": []
                    }, {
                    "value": 5,
                    "next": []
                },{
                    "value": 3,
                    "next": []
                    }, {
                    "value": 5,
                    "next": []
                }
            ]
            }, {
            "value": 5,
            "next": []
        },{
            "value": 3,
            "next": [
                {
                    "value": 3,
                    "next": []
                    }, {
                    "value": 5,
                    "next": []
                },{
                    "value": 3,
                    "next": []
                    }, {
                    "value": 5,
                    "next": []
                }
            ]
            }, {
            "value": 5,
            "next": []
        }
    ]
};

sumTree(tree);