Find the parent of a javascript tree object array

Question

Find the bellow parent child tree object I have created. I need to find the root parent of a given child id. For example child id - 242 root parent id is 238. There are similar questions have been asked and this is the one I found very similar to my question.

Convert parent-child array to tree

I have change the original code a bit But not working for child element. The issue is here. when it comes the recursive function with rootNode.children for loop will not execute since it does not loop through children. But if I change the for loop for (var i = 0; i < rootNode.length; i++) to for (var i = 0; i < rootNode.children.length; i++) then it break on first loop since does not have children. I'm sure with small code change this can make work.

var getParent = function (rootNode, rootId) {

if (rootNode.id === rootId)
    return rootNode;

//for (var i = 0; i < rootNode.children.length; i++) -- original code line not working first time 
for (var i = 0; i < rootNode.length; i++) {
    var child = rootNode[i];
    if (child.id === rootId)
        return child;

    if (typeof child.children !== 'undefined')
        var childResult = getParent(child, rootId);

    if (childResult != null) return childResult;
}
return null;
};

var mytree = [
{
    "id": 245,
    "parent": "0",
    "title": "project1",
    "children": [
        {
            "id": 246,
            "parent": "245",
            "title": "sub task 1"
        }
    ]
},
{
    "id": 238,
    "parent": "0",
    "title": "project2",
    "children": [
        {
            "id": 240,
            "parent": "238",
            "title": "sub task 2"
        },
        {
            "id": 242,
            "parent": "238",
            "title": "sub task 3",
            "children" : [
                {
                    "id": 241,
                    "parent": "242",
                    "title": "sub task 3.1"
                }
            ]
        }
    ]
},
{
    "id": 173,
    "parent": "0",
    "title": "project3"
}
];
console.log(JSON.stringify(getParent(mytree, 238)['title']));
console.log(JSON.stringify(getParent(mytree, 241)));

Nina Scholz · Accepted Answer · 2018-03-21 08:47:29Z

8

You need to iterate the given root node, because this is an array, not an object.

function getParent(root, id) {
    var node;

    root.some(function (n) {
        if (n.id === id) {
            return node = n;
        }
        if (n.children) {
            return node = getParent(n.children, id);
        }
    });
    return node || null;
}


var mytree = [{ id: 245, parent: "0", title: "project1", children: [{ id: 246, parent: "245", title: "sub task 1" }] }, { id: 238, parent: "0", title: "project2", children: [{ id: 240, parent: "238", title: "sub task 2" }, { id: 242, parent: "238", title: "sub task 3", children: [{ id: 241, parent: "242", title: "sub task 3.1" }] }] }, { id: 173, parent: "0", title: "project3" }];

console.log(getParent(mytree, 238));
console.log(getParent(mytree, 241));

.as-console-wrapper { max-height: 100% !important; top: 0; }

More a classical attempt

function getParent(root, id) {
    var i, node;
    for (var i = 0; i < root.length; i++) {
        node = root[i];
        if (node.id === id || node.children && (node = getParent(node.children, id))) {
            return node;
        }
    }
    return null;
}

var mytree = [{ id: 245, parent: "0", title: "project1", children: [{ id: 246, parent: "245", title: "sub task 1" }] }, { id: 238, parent: "0", title: "project2", children: [{ id: 240, parent: "238", title: "sub task 2" }, { id: 242, parent: "238", title: "sub task 3", children: [{ id: 241, parent: "242", title: "sub task 3.1" }] }] }, { id: 173, parent: "0", title: "project3" }];

console.log(getParent(mytree, 238));
console.log(getParent(mytree, 241));

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Mar 21, 2018 at 8:47

answered Mar 21, 2018 at 8:40

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

huykon225 Over a year ago

Thank for your answer but do you know the way to get from root of array?

Nina Scholz Over a year ago

do you meen you have an object as root? than you could wrap it in an array for calling, like getParent([rootObject], someId).

huykon225 Over a year ago

! I mean like your example, when I call getParent(mytree, 238) it will return an array from root id: 245

Nina Scholz Over a year ago

@huykon225, i don't understand the question. please add more information.

散漫的水元素 · Accepted Answer · 2018-03-21 12:44:15Z

0

I think my js tools can help you
https://github.com/wm123450405/linqjs

var mytree = [
{
    "id": 245,
    "parent": "0",
    "title": "project1",
    "children": [
        {
            "id": 246,
            "parent": "245",
            "title": "sub task 1"
        }
    ]
},
{
    "id": 238,
    "parent": "0",
    "title": "project2",
    "children": [
        {
            "id": 240,
            "parent": "238",
            "title": "sub task 2"
        },
        {
            "id": 242,
            "parent": "238",
            "title": "sub task 3",
            "children" : [
                {
                    "id": 241,
                    "parent": "242",
                    "title": "sub task 3.1"
                }
            ]
        }
    ]
},
{
    "id": 173,
    "parent": "0",
    "title": "project3"
}
];
//node.asEnumerable get a Tree object
//isAncestorOf to predicate the root node is or not the ancestor node of parameter
console.log(mytree.find(node => node.asEnumerable(node => node.children, node => node.id).isAncestorOf(241)));
console.log(mytree.find(node => node.asEnumerable(node => node.children, node => node.id).isAncestorOf(242)).title);

<script src="https://wm123450405.github.io/linqjs/libs/linq-js.min.js"></script>

edited Mar 21, 2018 at 12:44

answered Mar 21, 2018 at 9:12

散漫的水元素

92 bronze badges

1 Comment

WhatsThePoint Over a year ago

Code only answers arent encouraged as they dont provide much information for future readers please provide some explanation to what you have written

Collectives™ on Stack Overflow

Find the parent of a javascript tree object array

2 Answers 2

4 Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related