- React Native – Flexbox and Layout
Flexbox is the whole layout system — there is no grid and no float. The three defaults that differ from the web and bite constantly: `flexDirection` is `column`, `alignItems` is `stretch`, and `flex: 1` means something subtly different. Plus `gap`, wrapping rows of chips, and why `numberOfLines` is the only `text-overflow` you get.
- Java Data Types
Java splits every value into one of two worlds: primitives , which are raw values, and reference types , which are objects. There are exactly eight primitives and you need all of them. Everything else — String , arrays, your own classes — is a reference type. Knowing which world a value lives in…
- React – Props
Props are the arguments a component takes. Destructuring them in the signature, typing them with TypeScript, default values, the children prop, and passing functions down so a child can talk back to its parent. Plus the rule that explains half of all React bugs: props are read-only.
- Angular – Content Projection and ng-template
Writing a component that wraps content it does not own. Single-slot and multi-slot `<ng-content>`, selecting what lands where, `<ng-template>` and `<ng-container>` and the difference between them, and `ngTemplateOutlet` for the cases where a slot is not flexible enough.
- Docker – Images, Layers and Tags
An image is a stack of read-only layers and a container is a thin writable layer on top — which explains sharing, caching, image size and why editing a file in a running container changes nothing permanent. Reading `docker history`, what a tag really is, and why a digest is the only thing that pins an image.