Concepts in Frontend Dev, page 2
React Events: Pass, Don't Call
React handles user actions with event handler functions passed as props, like onClick={handleClick}. This is how you make buttons or forms interactive. The key mistake is calling the function (onClick={doIt()}), which runs on render, not on click.
CSS 'display': How Elements Occupy Space
The CSS display property defines an element's layout role: does it demand its own line (block) or share space (inline)? It's essential for everything from text flow to complex layouts with flex and grid.
Why Svelte Skips the Virtual DOM
Svelte skips the Virtual DOM, treating it as runtime overhead. It acts as a compiler, generating precise JavaScript to update the DOM directly. This avoids the 'diffing' step of frameworks like React, leading to smaller bundles and faster updates.
Conditional Rendering: Show UI Based on State
React uses plain JavaScript to decide what UI to show, which is essential for displaying loading states, errors, or user-specific content. The footgun: count && <Component /> will render a "0" if count is 0, not nothing.
CSS box-sizing: Predictable Element Sizing
The box-sizing property controls if padding and borders are added outside an element's width or carved out from inside. Using border-box makes layouts predictable, ensuring a width: 100px box is exactly 100px wide.
Lists and Keys in React
React turns arrays into UI with map, yet each child needs a unique key prop or you get console warnings. Filter first, then map. The footgun: forgetting keys or failing to include stable unique IDs in your source data.
Vue: Options API vs. Composition API
Options API organizes Vue components by property type (data, methods). Composition API organizes them by logical feature. Use Composition API for complex components with tangled logic or for creating reusable 'composable' functions.
TypeScript Interfaces: Naming the Shape of Your Data
An interface is a contract for an object's shape, caring what properties it has, not its class. Use it to define function parameters or API responses. The footgun: TypeScript allows objects with extra properties, checking only for the required ones.
CSS Pseudo-classes: Style Elements Based on State
CSS pseudo-classes style elements based on their state, not just their HTML structure. Use them for interactive states like :hover, form validation like :invalid, or structural position like :first-child.
Vue's Reactivity: JavaScript That Acts Like a Spreadsheet
Vue's reactivity system makes your data act like a spreadsheet: change a value, and dependent parts of your app update automatically. It works by wrapping your data in special objects. The footgun: reactivity is lost if you replace a whole object.
TypeScript Function Types: Expressions vs. Signatures
TypeScript describes function shapes with type expressions or call signatures. Use a simple expression like (s: string) => void for callbacks. For functions with properties, use a call signature. The footgun: parameter names are required in type expressions.
useEffect: Syncing React with the Outside World
useEffect synchronizes your component with systems outside React's control, acting as a bridge to the browser or network. It's for data fetching or subscriptions.
CSS Positioning: Taking Elements Out of Normal Flow
CSS position lets you override the default document flow. Think of it as telling an element to ignore its neighbors and listen to top/left coordinates instead. Use it for overlays, modals, and sticky headers.
Scaffolding a Vite Project with `create-vite`
Use create-vite to instantly generate a new web project with your chosen framework. It's the fastest way to start a Vue, React, or Svelte app without manual setup. The footgun is forgetting you can pass a --template flag to skip interactive prompts.
tsconfig.json: The Rulebook for Your TypeScript Project
The tsconfig.json file is the rulebook for the TypeScript compiler, defining which files to process and what rules to enforce. It's essential for setting strictness, module resolution, and output targets.
Thinking in React: Decomposing UIs into Components
Think of UIs not as one big page, but as a tree of reusable components. Start by breaking a design mockup into a hierarchy of pieces. The footgun is creating 'god components' that do too much; each component should have a single responsibility.
CSS Margin Collapsing: The Largest Margin Wins
Instead of adding up, vertical margins on adjacent block elements 'collapse' into one, taking the size of the largest margin. This explains why two paragraphs with margin: 1rem don't have 2rem of space between them. The footgun is assuming it's a bug.
ng new: Your Angular Project Starter Kit
The ng new command is your starter kit for any Angular project. It scaffolds a complete, runnable application with a standard folder structure and dependencies, letting you skip manual setup.
TypeScript Enums: Named Constants for Clarity
TypeScript enums give friendly names to a fixed set of values, like Status.Success instead of a magic number. Use them for API response codes or state machines. The footgun: default numeric enums are just numbers at runtime, making them hard to debug.
CSS Pseudo-elements: Styling Parts of an Element
Pseudo-elements style parts of an element not in the DOM, like a paragraph's first line or selected text. Use ::before/::after for decorative content or ::selection to style user highlights.
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