If you're dealing with forms in Angular on a regular basis one of the most powerful things you can learn is how to use the Control Value Accessor interface. The CVA interface is a bridge between FormControls and their elements in the DOM. A component extending the CVA interface can create a custom form control that behaves the same as a regular input or radio button.
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Angular 
Angular's Reactive Forms give us immense capabilities with its robust API, but the learning curve can be a bit steep from plain old template-driven forms that many are used to. This quick guide will explain Angular's main form elements and how to combine them, nest them, and dynamically create them in almost any scenario.
Jennifer Wadella
Angular
Are you moving from writing AngularJS to Angular apps? There's a lot to learn, but check out this quick guide on mistakes to avoid first!
1. Not Knowing How to Google for Angular
2. Not Installing & Using the Angular CLI
3. Not Taking the Time to Learn TypeScript Fundamentals
4. Getting Trolled by Syntax Changes
5. Not Learning the Basics of RxJS
6. Not Realizing the Nuances of Dependency Injection with Services
Jennifer Wadella
React 
Often times, particularly when dealing with complex nested data, React developers need to re-think the way they're structuring their component trees. In certain cases, when the data requires it, component trees can't be rendered in an iterative fashion, instead React developers must rely on recursion to display their data.
The Bitovi Team