svelte-development

Svelte 5 reactivity runes like $state, $derived, and $effect enable fine-grained state management and automatic UI updates with minimal boilerplate. $state declares reactive variables, $derived computes dependent values, and $effect runs side effects when state changes, eliminating the need for manual subscriptions and watchers.

$state defines mutable reactive source data that triggers updates when reassigned. $derived creates computed, read-only values derived from $state or other $derived runes, updating automatically without requiring explicit update logic.

Yes, Svelte stores and runes work together. Stores remain useful for cross-component state, while runes handle local component reactivity. You can combine both approaches—use $state for component-level reactivity and stores for shared, global state management.

SvelteKit enables SSR by rendering components server-side and hydrating on the client. Define routes in src/routes, use layout files for shared UI, and leverage load functions to fetch data server-side before rendering, reducing initial client-side work and improving performance.

Svelte provides transition and animation directives (transition:fade, animate:flip) that declaratively apply CSS-based effects to DOM changes. Combine these with runes to trigger state changes that automatically animate element entry, exit, and reordering without manual JavaScript.

TypeScript is optional but recommended. SvelteKit supports TypeScript out of the box with type checking for routes, components, and store definitions, improving developer experience and catching errors early without extra configuration.