There are few code paths that lead to same purpose: to create a tree node. They differ in effeciency and use patterns

You specity a tree and its nodes in HTML, relying upon dojo to parse it and turn into widgets. That is a slowest way, but nice for small trees or if only tree top is specified and the rest is created later. dojo widget parser walks DOM and creates a special structure. The next pass creates widgets from the structure.

The generic widget creation routine. It basically runs the operations in order: Mix in widget properties from parameters/markup Register widget in widget.Manager Call buildRendering to make fill template and create domNode Call initialize Call postInitialize. registers widget as a child of its parent and after it creates all subwidgets Call postCreate Note that initialize is called in pre-order: parent is initialized before children, postInitialize is called in post-order: a child is postCreated before its parent.

If you create nodes with javascript, then you run create calls manyally. So parents are naturally created (and postCreated) before children There seem to be no good way to distinguish betwen markup creation and manual creation. From the one hand its seems good, because allows reuse of generic creation code. From the other hand code paths going through this code are subtly different. The reliable thing is that initialize will process widget after its domNode is built, BUT it should not assume anything about children. nodeCreate event is fired on initialization also. If you want to know anything about children and do something at this point - check addChild, but not node creation.

children array may be empty contain widgets, e.g if created from markup, or someone created them before parent and pushed in contain data objects, that will be turned into widgets when parent expands. isFolder comes into play only when there are no children. It allows creation of empty folders, with UNCHECKED state that can be filled later.