遍历包含数组的JSON对象，该数组包含的对象包含包含etc的数组

Question

I'm making an API call that returns a large tree of JSON data. It's structured like this:

{
...
children: [ {
             ... children: [ ... ], ...
            }, ... (10 or more objects) ]
...
}

Eventually (it's very large!) the children array will contain objects without a children array. I need to loop through the whole object and get all the elements that have property content-kind: "Video" ; if it has a content-kind property it is guaranteed not to have a children array.

Sometimes what might happen is this:

children: [{ content-kind: "Video" }, { children: [ ... ] }, ...]

I want to grab the object with the content-kind: "Video" but still search the one with the children array.

I've tried every combination of while and for loops I could think of, but I couldn't solve my problem.

---

EDIT: Best attempt:

var e = json.children;
while (e.children) { e = e[0].children; }
if (e.content_kind == "Video") return e;

Obviously this won't work.

Answer 1

To traverse the tree and call handle_node() for every node, the recursion would be

function traverse(node) {
  if(node.children) node.children.forEach(traverse);
  handle_node(node);
}

Read more about tree traversal .

Answer 2

If you have nested elements and you don't know how deep is your tree/graph/whatever, you should use recursion. This is a simple pseudo-code that might help you a bit:

function traverseTree(tree) {
    var results = [];

    for (var i = 0; i < tree.length; i++) {
        if (tree[i].hasOwnProperty('content-kind') && tree[i]['content-kind'] === 'Video') {
            results.push(tree[i]);
        } else if (tree[i].hasOwnProperty('children')) {
            results = results.concat(traverseTree(tree[i].children)); // here's the magic
        }
    }

    return results;
}

Here's the JSFiddle: http://jsfiddle.net/2hannxqr/

Answer 3

You could make a recursive function that loops around and around, OR you could semi-fake-badly-parse the JSON yourself:

json = '{"children":[{"children":[{"children":[{"content-kind":"video","foo":"bar"},{"content-kind":"video","foo":"baz"}]}]}]}';
objects = json.match(/{"content-kind":"video"[^}]+}/g);

objects will now be an array of JSON objects:

['{"kind":"video","foo":"bar"}', '{"kind":"video","foo":"baz"}']

which you can loop through, JSON.parse() and read.

This method will require a very precise JSON structure and key order and encoding etc.