Question

I’ve a hierarchical json object, I want to traverse it and attach a parent node to each element. This is what I’ve done

function attach_back_reference(hierarchy, parent){
    hierarchy.parent = parent;
    for(var i in hierarchy){
        if(jQuery.isPlainObject(hierarchy[i]))
            attach_back_reference(hierarchy[i], hierarchy);
    }
}

But this is giving error. Maximum call stack size exceeded

Answer 1

Since you do

for(var i in hierarchy){

after adding the parent property, one value of i will be "parent", so you end up setting the child as its own grandparent infinitely.

You can see this in

var o = {};
o.x = o;
for (var i in o) { alert(i); }

which alerts "x".

Move the loop to the top.

function attach_back_reference(hierarchy, parent){
    for(var i in hierarchy){
        if(jQuery.isPlainObject(hierarchy[i]))
            attach_back_reference(hierarchy[i], hierarchy);
    }
    hierarchy.parent = parent;
}

Alternatively, if you only need this to work on newer interpreters, you can try making the parent property unenumerable : javascript defineProperty to make an attribute non enumerable