Magento 2: uiElement registerNodes Defaults

Wrapping up our uiElement defaults, we have the registerNodes defaults

#File: vendor/magento/module-ui/view/base/web/js/lib/core/element/element.js
defaults:{
    /* ... */
    registerNodes: true,        
    /* ... */
}

This is another node that you don’t need to worry too much about. Magento uses this to identify the uiElement objects in the Magento_Ui/js/lib/knockout/extender/bound-nodes extension.

The Magento_Ui/js/lib/knockout/extender/bound-nodes RequireJS module is included as a dependency in the Knockout.js bootstrap module. It’s initial loading will wrap the ko.applyBindings and ko.cleanNode method with some custom code that (appears to) store certain bound nodes and view models in a javascript WeakMap. However, if the passed in view model does not contain the registerNodes flag, then Magento skips adding it

#File: vendor/magento/module-ui/view/base/web/js/lib/knockout/extender/bound-nodes.js
if (data && data.registerNodes) {
    addBounded(data, node);
}

The module also returns an object with an interface to the WeapMap that stores the bound nodes. You can see it in action with the following code (run this on the Customers -> All Customers page)

reg = requirejs('uiRegistry')
viewModel = reg.get('customer_listing.customer_listing.customer_columns');
boundNodes = requirejs('Magento_Ui/js/lib/knockout/extender/bound-nodes')

console.log( boundNodes.get(viewModel) );

Unfortunately, I’m not sure what purpose this Magento_Ui/js/lib/knockout/extender/bound-nodes registry serves. Between my lack of understanding w/r/t Knockout.js internals and Magento’s love of jQuery Deferred objects, it’s not 100% obvious what all this is for.

However – as a defaults that you need to worry about when creating UI Components, this is one you can safely ignore.