Effective Error Handling in SvelteKit

SvelteKit provides a robust framework for managing errors in your application, enhancing user experience and simplifying debugging processes.

Key Concepts

• Error Handling: SvelteKit enables you to catch and manage errors during your application's rendering phase.
• Load Functions: While fetching data, errors may arise. SvelteKit offers built-in mechanisms to handle such scenarios effectively.

Main Features

• Error Handling Mechanism: Customize error handling logic within your routes.
• Error Pages: Create dedicated error pages to inform users when something goes awry.

How to Handle Errors

• The handleError function allows you to tailor how errors are logged or displayed.
• Set this function up in your hooks.js file.
• Create error boundaries in your components to catch errors locally.
• This approach lets you show fallback content without crashing the entire application.

Error Boundaries:

<script>
    import { onMount } from 'svelte';

    let data;
    let error;

    onMount(async () => {
        try {
            const res = await fetch('/api/data');
            if (!res.ok) throw new Error('Network response was not ok');
            data = await res.json();
        } catch (err) {
            error = err.message;
        }
    });
</script>

{#if error}
    <p>Error: {error}</p>
{:else if data}
    <p>Data: {data}</p>
{/if}

Using handleError:

// src/hooks.js
export function handleError({ error, event }) {
    console.error(error);
    return { message: 'Something went wrong!', status: 500 };
}

Creating Custom Error Pages

• Define a custom error page by creating a +error.svelte file within your routes.
• This file automatically displays errors that occur in that specific route.

<!-- src/routes/+error.svelte -->
<script>
    export let status;
    export let message;
</script>

<h1>Error {status}</h1>
<p>{message}</p>

Conclusion

Effectively handling errors in SvelteKit not only enhances user experience but also strengthens the resilience of your application. By implementing handleError, using error boundaries, and crafting custom error pages, you can ensure your application gracefully manages unexpected challenges.