Iteratively create layers of json

Question

I have several arrays of strings that I want to generate a object out of. An example is this. Given I have:

let graph = {}
let a = ["Vehicle", "Car", "Sport"]
let b = ["Vehicle", "Car", "Van"]
let c = ["Vehicle", "Truck", "4x4"]

I want to make a function that I can pass a into and it would update graph to be:

{
    name: "Vehicle",
    children: [
        {
            name: "Car",
            children: [
                "Sport"
            ]
        }
    ]
}

I then pass b into the function and graph sees that "Vehicle" > "Car" already exists so it just pushes "Van" into the children. Then when c is passed it pushes a child onto the Vehicle children. I am having trouble as with a loop I am not able to account for the fact that the input can be of any length (not just 3). How can I loop through the depth of an object like this?

I see posts like this about once a week. That pattern is to write a recursive function which takes in a list and the 'current location' in the graph, then recursively iterate down the list. Do that for each piece of data (a, b, c) and customize for your specific structure — Cody E, Apr 23 '21 at 23:08
FYI this is called a tree (or "forest" if there are multiple roots), which might help with searching. — ggorlen, Apr 23 '21 at 23:11
This is not valid tree, Why 3rd nested node contain just array ? `children[0].children = [ "Sport" ]` — Nur, Apr 24 '21 at 08:04

Nur · Accepted Answer · 2021-04-24T14:06:38.013

As I said in the comments box that, Your expected result isn't valid node tree, Because 3rd nested node should not contain array.

Anyway Here is my answer:

const nodes = new Map([["graph", { children: [], name: 'graph' }]]); // 'graph' is the root node 
const entries = [["Vehicle", "Car", "Sport"], ["Vehicle", "Car", "Van"], ["Vehicle", "Truck", "4x4"]];

function* createNodeIds(entrie, parentId, deep = 0) {
    const name = entrie.shift();
    const nodeId = parentId + '.' + name;
    yield [parentId, nodeId, name, ++deep];
    while (entrie.length)
        yield* createNodeIds(entrie, nodeId, deep);
}

for (const entrie of entries)
    for (const [parentId, nodeId, name, deep] of createNodeIds(entrie, 'graph'))
        if (!nodes.has(nodeId)) {
            const node = { name, children: [] }
            nodes.set(nodeId, node);
            nodes.get(parentId).children.push(deep > 2 ? name : node)
        }

console.log(nodes.get('graph.Vehicle'));

Iteratively create layers of json

1 Answers1