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 · 2018-03-21T08:47:29.940

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; }

Thank for your answer but do you know the way to get from root of array? — huykon225, Jan 31 '20 at 11:02
do you meen you have an object as root? than you could wrap it in an array for calling, like `getParent([rootObject], someId)`. — Nina Scholz, Jan 31 '20 at 11:15
! I mean like your example, when I call `getParent(mytree, 238)` it will return an array from root *id: 245* — huykon225, Jan 31 '20 at 14:45
@huykon225, i don't understand the question. please add more information. — Nina Scholz, Feb 01 '20 at 09:40

散漫的水元素 · Answer 2 · 2018-03-21T12:44:15.547

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>

Code only answers arent encouraged as they dont provide much information for future readers please provide some explanation to what you have written — WhatsThePoint, Mar 21 '18 at 09:19

Find the parent of a javascript tree object array

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