Results Summary
Performance
Bundle Size
Build Time
Load Time
Complexity
Performance Metrics
Bundle Analysis
Build Info
About the Svelte Weather Front App
Status
-
Lint
-
Build
-
Test
Links
Usage Instructions
First, follow the repo setup instructions.
Then cd into ./apps/svelte/
and and use the following commands:
- Dev Command npm run dev
- Test Command npm run test
- Lint Command npm run lint
- Build Command npm run build
- Start npm start
npm run verify
from the root of the project.
App Requirements
The purpose of this project, was to build the same identical app in every frontend framework, in order to benchmark and compare their performance. As such, each app is built to meet identical requirements, which are then verified with the test suite.
Technical Requirements
- Binding user input and validation
- Fetching external data asynchronously
- Basic state management of components
- Handling fallback views (loading, errors)
- Using browser features (location, storage, etc)
- Logic blocks, for iterative content and conditionals
- Lifecycle methods (mounting, updating, unmounting)
Feature Requirements
- 🌦️ Live weather conditions
- 📅 7-day weather forecast
- 🔍 City search functionality
- 📍 Geolocation support
- 💾 Persistent location storage
- 📱 Responsive design
- ♿ Accessible interface
- 🎨 Multi-theme support
- 🧪 Fully unit tested
- 🌐 Internationalized

Svelte Implementation
Svelte Stores
The weather-store.js
uses Svelte's writable stores for global state management. Store actions are grouped in an object, providing a clean API for weather operations.
Reactivity Without Framework Runtime
Svelte compiles away at build time, meaning no virtual DOM or framework code ships to the browser. Reactive statements using $:
syntax automatically recompute when dependencies change.
Built-in State Management
No external state management library needed - Svelte's stores handle global state with automatic reactivity. Components can subscribe to stores using the $store
syntax.
SvelteKit Integration
Uses SvelteKit's file-based routing with +page.svelte
and +layout.svelte
. The $app/environment
module provides SSR-safe environment detection with the browser
check.
Simplified Component Syntax
Svelte components use <script>
, <template>
, and <style>
sections, but with less boilerplate than other frameworks - no need for explicit return statements or render functions.
About Svelte
Real-world App
Since the weather app is very simple, and doesn't show of the full features of a framework, it may be helpful to see a more practical implementation of a Svelte app. So, checkout:Intro to Svelte
About Svelte
Svelte compiles your code at build time into minimal JS with no runtime framework. That makes it very fast, with tiny bundle sizes. It’s one of the most loved frameworks in surveys like Stack Overflow’s. The syntax is simple and elegant, and it feels closer to writing plain HTML, CSS and JS. The main drawback is a smaller ecosystem compared to React or Vue.
My thoughts on Svelte
Svelte is just fun. There's something magical about writing count += 1
and having the UI automatically update. No useState
, no useEffect
, no ref()
- just assign to a variable and it reacts. This is how UI frameworks should work.
Unlike React or Vue, Svelte doesn't ship a runtime. Your components get compiled into highly optimized vanilla JavaScript at build time. The result? Tiny bundles, blazing fast performance, and surprisingly readable compiled output. Our weather app compiles down to around 15KB, which is frankly ridiculous for a full-featured application.
The $:
reactive statements are brilliant for computed values - $: tempDisplay =
${temp}°C` just works and updates whenever
temp` changes. Svelte stores handle global state beautifully, and the automatic subscription cleanup means you never have to worry about memory leaks.
The template syntax feels natural - {#if}
, {#each}
, and {#await}
blocks handle conditional rendering and async data elegantly. Two-way binding with bind:value
eliminates the usual form boilerplate you'd write in React.
For our simple weather app, we didn't need Svelte's built-in animations or transitions. But Svelte is my go to choice for nearly all my personal projects, as these features become incredibly powerful. The transition:
and animate:
directives can make your UI feel incredibly polished with minimal code.
Choosing a Framework
Stack Match
Not sure if Svelte is right for your project? Use Stack Match to select your preferences and get a tailored recommendation based on the benchmark data.
