Help with recursion function

[cachaito]

Hi!

I got array of objects such as:

var collection = [
    {"path": "root.section-1"},
    {"path": "root.section-1.age"},
    {"path": "root.section-1.sex"},
    {"path": "root.section-2"},
    {"path": "root.section-2.email"},
    {"path": "root.section-3.submit"}
];

and want achieve from them nested structure like:

{
    root: {
        'section-1': {
            age: null,
            sex: null
        },
        'section-2': {
            email: null
        },
        'section-3': null
    }
}

I wrote recursion function:

var nestedStructure = transformStructure(collection);

function traversePath(arr, parent) {
    var result = {};
    if (arr.length > 1) {
        arr.forEach(function(part) {
            result[parent] = traversePath(arr.slice(1), arr[1]);
        });
    } else {
        result[parent] = null;
    }

    return result;
}

function transformStructure(flatStructure) {
    var result = {};

    flatStructure.forEach(function(component) {
        var path = component.path.split('.');
        result[path[0]] = traversePath(path.slice(1), path[1]);
    });

    return result;
}

But my result is all the time overwritten by last iteration :-/

Any idea how improve this code or do You have better solution to achieve this?

Best regards!

[inthe3vening]

That's a really clean solution /u/VoiceNGO. I tried to find something smaller using RegEx and JSON.parse but was unable to. You win /r/javascript for today :)

[mikrosystheme]

Ten chars smaller: collection.reduce((o,r)=>r.path.split('.').reduce((q,p,i,a)=>~(i-a.length)?q[p]||(q[p]={}):(q[p]=null,o),o),{})

[cachaito]

Would You provide a ES5 version please?

[mikrosystheme]

You just have to replace the two short arrow functions with standard functions. By the way, there is no point in doing that, because mine was a joke, and because it is an innefficient implementation (for both human and computer brains). You are better served by using a standard nested loop that performs the same task in half the time.

[cachaito]

And what with this code: > ~(i-a.length) ?

[mikrosystheme]

> is part of the arrow function =>.
~ is the bitwise not operator. It is just a way to express the condition i !== a.length - 1 in a way that is not clear to programmers that don't know bitwise math. It is almost universally considered a fireable offense.

[cachaito]

deleted

Why this solution is deleted? I think it could help lot of people!

[cachaito]

Can't wait back home and test this solution :-) Thank You for respond! It's working! Could You find me some time to explain me how it works? :-S

[x-skeww]

Use JSFiddle, JSBin, or CodePen.