CODEWITHSUNDEEP
javascriptarraysunderscore.js
Thiago Miranda de Oliveira
Thiago Miranda de Oliveira

Reputation: 5930

Iterate over array with unknow number of sublevels underscore.js

I have an array of objects like this:

[{
name: "Peter",
childs: [{
    name: "John",
    childs: [{
        name: "Joseph",
        childs: []
    }]
}]
},
{
    name: "Carl",
    childs: [{
        name: "Sam",
        childs: []
    }]
}]

Where each person can have children and each of these children can have any number of children and so on. Does anyone know a good way to perform this on underscore.js?

Upvotes: 1

Views: 1853

Answers (2)

saml
saml

Reputation: 6802

It seems like you're asking how to do tree traversal, but not anything unique to underscore.js. You can do a depth first traversal this way:

var children = [{name: "Peter", childs: [...]}, ...]
function traverseAndPrint(tree) {
    for (var i = 0; i < tree.length; i++) {
        console.log(tree[i].name);
        traverseAndPrint(tree[i].childs);
    }
}

If you need to perform an arbitrary action on each element, you could do the following:

function traverseAndCallFunction(tree, functionToCall) {
    for (var i = 0; i < tree.length; i++) {
        functionToCall(tree[i]);
        traverseAndPrint(tree[i].childs);
    }
}

where functionToCall is a function that takes a child object (according to your example)

I don't see why you'd need underscore.js to do tree traversal.

Upvotes: 3

I Hate Lazy
I Hate Lazy

Reputation: 48761

Sorry, I don't know how specifically in underscore, but it seems a simple recursive function would be easy enough for you.

var data = [{ 
   name: "Peter",
   childs: [{
       name: "John",
       childs: [{
           name: "Joseph",
           childs: []
       }]
   }, { 
       name: "Carl",
       childs: [{
           name: "Sam",
           childs: []
       }]
   }]
}];

function trav(data, fn) {
    data.forEach(function(item) {
        for (var p in item)
            if (p === "childs")
                trav(item[p], fn);
            else
                fn(item[p], p);
    });
}

trav(data, function(val, prop) {
    console.log(prop, val);
});

Upvotes: 1

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