How to Build a Sveltekit Frontend and Connect it to a Backend?

in this tutorial, you’ll build a to do list application using sveltekit and connect it to a managed backend service powered by back4app this guide is designed for you if you want to master essential crud (create, read, update, delete) operations and create a dynamic, responsive interface using sveltekit by the end of this tutorial, your application will seamlessly interact with a backend that handles data storage, authentication, and more developing a full stack application can be complex due to backend configuration and database management to simplify your workflow, we use back4app—a robust backend as a service—so you can focus on crafting an outstanding sveltekit frontend back4app provides a fully managed nosql database, authentication, cloud code for custom logic, and sdks for smooth integration this enables you to build and deploy scalable applications without managing server infrastructure key takeaways by following this tutorial, you will initialize a modern sveltekit project using vite integrate a backend service to manage your application’s data implement essential crud operations for a dynamic to do list deploy your fully functional application using containerized workflows on back4app prerequisites before you begin, ensure you have node js and npm installed on your machine verify by running node v and npm v basic sveltekit knowledge , including routing, load functions, and reactive variables a back4app account to manage your backend services sign up at back4app https //www back4app com/ if you haven’t already with these prerequisites in place, you’re ready to start building your project project setup begin by setting up your local development environment and initializing a new sveltekit project ensure you have node js (lts version) installed if not, download it from nodejs org https //nodejs org/ create your sveltekit project by running npx sv create todo app when prompted, choose the sveltekit options that best suit your project (e g , skeleton project, typescript if desired) navigate into your project directory cd todo app start the development server to verify the setup npm run dev your sveltekit app should now open in your browser with the frontend ready, proceed to create your backend on back4app creating the todo backend back4app offers a fully managed backend service powered by parse it includes a nosql database, authentication, cloud code, and auto generated apis follow these steps to set up your backend log in to your back4app dashboard https //www back4app com/ and click "create a new app " name your app (for example, todoapp ) and select nodejs/parse as the backend type navigate to "database" > "browser" , click "create a class" , and choose "custom" name the class task and configure it for public read and write (you can refine these permissions later) in the task class, add the following fields title (string) – the task title description (string) – details about the task completed (boolean) – task completion status duedate (date) – the deadline for the task click "save" to create the schema integrating back4app with sveltekit you will use the parse javascript sdk to connect your sveltekit app to the back4app backend install the parse sdk npm install parse configure the sdk by editing the src/app html or creating a dedicated module (e g , src/lib/parseclient js ) for example, create src/lib/parseclient js with the following import parse from 'parse/dist/parse min js'; const parse app id = 'your application id'; const parse js key = 'your javascript key'; const parse server url = 'https //parseapi back4app com/'; parse initialize(parse app id, parse js key); parse serverurl = parse server url; export default parse; you can now import this module in your sveltekit routes or components to interact with back4app developing the frontend your sveltekit application will consist of routes and components to add, display, update, and delete tasks leverage sveltekit’s file based routing and reactive variables for dynamic updates structuring your components create a src/lib/components folder to organize your components mkdir p src/lib/components you will create the following components taskform svelte – for adding new tasks tasklist svelte – to display the list of tasks taskitem svelte – to represent individual tasks taskform svelte this component renders a form that captures task details and submits them to back4app \<script> import { createeventdispatcher } from 'svelte'; import parse from '$lib/parseclient'; let title = ''; let description = ''; const dispatch = createeventdispatcher(); async function handlesubmit(event) { event preventdefault(); try { const task = parse object extend('task'); const task = new task(); task set('title', title); task set('description', description); task set('completed', false); await task save(); dispatch('refresh'); title = ''; description = ''; } catch (error) { console error('error adding task ', error); } } \</script> \<form on\ submit|preventdefault={handlesubmit}> \<input type="text" placeholder="task title" bind\ value={title} required /> \<input type="text" placeholder="description" bind\ value={description} required /> \<button type="submit">add task\</button> \</form> taskitem svelte this component represents an individual task, with buttons to toggle its completion status or delete the task \<script> import parse from '$lib/parseclient'; export let task; export let refresh; async function togglecomplete() { try { const query = new parse query('task'); const tasktoupdate = await query get(task id); tasktoupdate set('completed', !task completed); await tasktoupdate save(); refresh(); } catch (error) { console error('error updating task ', error); } } async function deletetask() { try { const query = new parse query('task'); const tasktodelete = await query get(task id); await tasktodelete destroy(); refresh(); } catch (error) { console error('error deleting task ', error); } } \</script> \<div class="task item {task completed ? 'completed' ''}"> \<div> \<h3>{task title}\</h3> \<p>{task description}\</p> \</div> \<div> \<button on\ click={togglecomplete}> {task completed ? 'undo' 'complete'} \</button> \<button on\ click={deletetask}>delete\</button> \</div> \</div> tasklist svelte this component displays all tasks by iterating over an array and rendering each task using the taskitem component \<script> import taskitem from '$lib/components/taskitem svelte'; export let tasks = \[]; export let refresh; \</script> {#if tasks length === 0} \<p>no tasks available\</p> {\ else} {#each tasks as task (task id)} \<taskitem {task} {refresh} /> {/each} {/if} +page svelte (main route) in your main sveltekit route (e g , src/routes/+page svelte ), manage the state of tasks and integrate the components \<script> import { onmount } from 'svelte'; import parse from '$lib/parseclient'; import taskform from '$lib/components/taskform svelte'; import tasklist from '$lib/components/tasklist svelte'; let tasks = \[]; async function fetchtasks() { try { const task = parse object extend('task'); const query = new parse query(task); const results = await query find(); tasks = results map(task => ({ id task id, task tojson() })); } catch (error) { console error('error fetching tasks ', error); } } onmount(fetchtasks); \</script> \<div class="container"> \<h1>to do list\</h1> \<taskform on\ refresh={fetchtasks} /> \<tasklist {tasks} refresh={fetchtasks} /> \</div> styling the application create a global stylesheet (e g , src/app css ) to add basic styling container { max width 600px; margin 40px auto; padding 0 20px; text align center; font family sans serif; } container h1 { margin bottom 20px; } form { display flex; flex direction column; align items center; gap 10px; margin bottom 20px; } form input\[type="text"] { width 80%; max width 400px; padding 8px; box sizing border box; font size 1rem; } form button { padding 8px 16px; cursor pointer; font size 1rem; border none; background color #eaeaea; transition background color 0 2s ease; } form button\ hover { background color #ccc; } task item { display flex; flex direction column; align items center; justify content center; gap 12px; border 1px solid #ccc; border radius 6px; padding 15px; margin 10px 0; background color #fafafa; text align center; transition background color 0 2s ease; } task item completed h3, task item completed p { text decoration line through; color #888; } task item h3 { margin 0; font size 1 1rem; } task item p { margin 0; font size 1rem; } task item button { padding 6px 12px; border none; background color #eaeaea; cursor pointer; font size 0 9rem; } task item button\ hover { background color #ccc; } @media (min width 600px) { task item { flex direction row; } } import this stylesheet in your src/app html or main layout file deploying the frontend on back4app web deployment back4app web deployment provides a containerized environment to host your sveltekit application configuring vite for production update your vite config js if necessary to set the base path for a containerized environment import { sveltekit } from '@sveltejs/kit/vite'; import { defineconfig } from 'vite'; export default defineconfig({ plugins \[sveltekit()], base ' /', }); generate the production build npm run build creating a dockerfile before you can test your docker container locally, you need to install adapter node which builds your site for node js to do this, run the command on your terminal npm i d @sveltejs/adapter node after installing the adapter node , open the svelte config js file replace the code there with the code block below import adapter from '@sveltejs/adapter node'; / @type {import('@sveltejs/kit') config} / const config = { &#x9;kit { &#x9; // adapter auto only supports some environments, see https //svelte dev/docs/kit/adapter auto for a list &#x9; // if your environment is not supported, or you settled on a specific environment, switch out the adapter &#x9; // see https //svelte dev/docs/kit/adapters for more information about adapters &#x9; adapter adapter() &#x9;} }; export default config; now, create a dockerfile in your project root with the following content from node 22 alpine as builder workdir /app copy package json / run npm ci copy run npm run build run npm prune production from node 22 alpine workdir /app copy from=builder /app/build build/ copy from=builder /app/node modules node modules/ copy package json expose 3000 env node env=production cmd \[ "node", "build" ] testing the docker container locally build your docker image docker build t todo frontend run the container docker run p 3000 3000 todo frontend open http //localhost 3000 in your browser to verify that your sveltekit app is served correctly deploying to back4app initialize a git repository, add your project files, and commit git init git add git commit m "initial commit for back4app deployment" git branch m main git remote add origin \<your github repository url> git push u origin main log in to back4app web deployment https //www back4app com/containers click "create new app" , provide your project name, and select your github repository authorize back4app and choose dockerfile deployment confirm the build settings and click "deploy" to start the deployment process monitoring your deployment after deployment, use the back4app dashboard to view logs for debugging monitor container performance and resource usage trigger rebuilds on new commits configure custom domains if needed access your live application at https //todoapp ku5ofg8s b4a run/ https //todoapp ku5ofg8s b4a run/ https //todoapp ku5ofg8s b4a run/ testing and debugging after deployment, confirm that your sveltekit frontend properly communicates with the back4app backend api verification use your browser’s developer tools (f12 → network) to inspect api calls task operations add, complete, and delete tasks via the ui and verify updates in the back4app database browser error handling check console logs for errors and test edge cases such as submitting empty tasks performance testing simulate slow network conditions using browser tools to assess responsiveness best practices for using back4app with sveltekit to optimize your application efficient requests use batch operations when handling multiple tasks const tasks = \[task1, task2, task3]; parse object saveall(tasks); optimized queries retrieve only necessary fields query select('title', 'completed'); environment management store sensitive keys in environment variables vite parse app id=your app id vite parse js key=your js key security use acls to restrict access task setacl(new parse acl(parse user current())); backend offloading leverage cloud code for complex logic to reduce api exposure conclusion you have now built a full stack to do list application by creating a sveltekit frontend, integrating it with back4app’s backend, and deploying it using containerized workflows this tutorial guided you through every step—from local development to cloud deployment—ensuring smooth interaction between your sveltekit ui and backend services looking ahead, consider enhancements like real time updates, improved authentication, and third party integrations for further learning, visit the back4app documentation https //www back4app com/docs and explore community resources