Question

Consider the following example:

<script>
var McDuffFamily = {
    name: "Jack McDuff I",
    children: [
        {
            name:"Jack McDuff II",
            children: [
                {
                    name:"Jack McDuff III",
                    children: [
                        {
                            name:"Jack McDuff IV"
                        },
                        {
                            name:"Jonh McDuff I",
                            children: [
                                {
                                    name:"Jonh McDuff I",
                                    children: []
                                }
                            ]
                        }
                    ]
                },
                {
                    name:"Shena McDuff"
                }
            ]
        },
        {
            name:"Poor bastard",
            children: [
                {
                    name:"Citzen I",
                    children: [
                        {
                            name:"Darth Vader"
                        }
                    ]
                },
                {
                    name:"Citzen II",
                    children: []
                }
            ]
        }
    ]
};
</script>

Is there any painless way to retrieve the names of all “Jack McDuff I” descendents?

Answer 1

Not using recursion:

var tree =[McDuffFamily];
var kids = [];
for (i=0; i < tree.length; i++) {

   tree[i] && tree.push.apply(tree, tree[i].childrens)
   kids.push(tree[i]);
}
kids; // all children

Breakdown of the weird part:

tree[i] && tree.push.apply(tree, tree[i].childrens);

tree[i] && is used with short-circuit evaluation ensuring that tree[i] is not null when I call tree[i].children

tree.push.apply(tree, tree[i].childrens); using apply which allows me to call a function, in this case Array.push, which takes any number of arguments on tree. So that line basically becomes tree.push(child0, child1, ... childn);.

so now tree.length has been increased by the number of children on the current child.