How do I "pick" children in javascript?

So why does this:

const ObjectA = runtime.objects.ObjectA.getFirstInstance();
const ObjectChildren = ObjectA.children();
for (let j = 0; j < ObjectChildren.length; j++) {
 if (ObjectChildren[j].objectType.name === "ObjectB") {
 	ObjectChildren[j].destroy();
	}
}

Update: Apparently .children() does not return an array as in a regular javascript array, that's all I know tho.

Apparently, there are three types of arrays here:

.The javascript arrays

.The construct array plugin arrays

.This weird kind I'm getting which seems to be the same kind of array you get by creating a json array in construct (which, fun fact, I've noticed starts with "c2Array: true")

please help ><

edit: also for some reason the .getAllInstances() method returns a regular JS array so I wonder what's the criteria