10 Svelte Best Practices

Svelte is a popular JavaScript framework that is used to create user interfaces. It is known for its speed and efficiency, and is a great choice for developers who want to create fast and responsive web applications.

However, like any other framework, there are certain best practices that should be followed when using Svelte. In this article, we will discuss 10 Svelte best practices that will help you create better applications and improve your development workflow.

1. Use CSS-in-JS

CSS-in-JS allows you to write your styles in the same file as your component, which makes it easier to keep track of and maintain. It also helps with performance since Svelte can compile the CSS into JavaScript code that is optimized for faster loading times.

CSS-in-JS also gives you more control over how your components look and feel. You can use variables, functions, and other features to make sure your components are consistent across different browsers and devices. Plus, you can easily add custom styling without having to create a separate CSS file.

2. Avoid using the state store unless necessary

The state store is a powerful tool, but it can also be a source of complexity and confusion if used incorrectly.

When using the state store, you should strive to keep your code as simple and straightforward as possible. This means avoiding unnecessary nesting or complex logic in your components. Instead, try to use simpler methods such as props and local variables whenever possible.

Additionally, when using the state store, make sure that all changes are properly tracked and logged so that any bugs or issues can be quickly identified and fixed. Finally, always remember to clean up after yourself by unsubscribing from stores and disposing of subscriptions when they’re no longer needed.

3. Don’t use Svelte stores for small bits of data

Svelte stores are designed to be used for larger pieces of data that need to be shared across multiple components. If you use a store for small bits of data, it can lead to unnecessary complexity and performance issues.

Instead, try using props or local state variables when dealing with smaller pieces of data. This will help keep your codebase clean and organized, as well as improve the overall performance of your application.

4. Use the onMount lifecycle hook to fetch data

The onMount lifecycle hook is called when the component is mounted to the DOM, which means that it’s the perfect time to fetch data from an API or other external source. This ensures that your component will always have access to the latest data and won’t be stuck with stale information.

It also helps keep your code organized by keeping all of your data-fetching logic in one place. This makes it easier to debug any issues you may encounter down the line.

5. Use a component library

Component libraries provide a set of pre-built components that you can use in your Svelte projects. This saves time and effort, as you don’t have to build the components from scratch.

Component libraries also help ensure consistency across your project. By using the same components throughout, you can create a unified look and feel for your application. Additionally, component libraries often come with helpful documentation and tutorials, making it easier to learn how to use them.

6. Keep your components as simple as possible

When components become too complex, they can be difficult to maintain and debug. Additionally, if you have multiple developers working on the same project, it’s important that everyone is able to understand what each component does without having to spend a lot of time deciphering code.

By keeping your components simple, you’ll make them easier to read, more efficient, and less prone to errors. This will also help ensure that all members of your team are on the same page when it comes to understanding how the application works.

7. Use named slots instead of unnamed ones

Named slots allow you to easily identify which part of the component is being used for what purpose. This makes it easier to debug and maintain your code, as well as making it more readable. It also allows you to pass data from parent components into child components without having to manually set props or use a store.

Using named slots also helps keep your components organized and modularized, allowing you to reuse them in different contexts. This can save time when building complex applications with multiple components.

8. Use svelte/store over writable()

Svelte/store is a built-in store that provides an easy way to manage state in Svelte. It’s more efficient than writable() because it uses reactive declarations, which means the code will only run when something changes. This makes svelte/store faster and easier to use than writable(). Additionally, svelte/store also has better support for asynchronous operations, making it ideal for managing complex data structures.

9. Use $: prefixes with caution

The $: prefix is used to denote reactive statements, which means that the statement will be re-evaluated whenever its dependencies change. This can lead to performance issues if not used correctly, as it can cause unnecessary re-renders of components and slow down your application.

Therefore, it’s important to use the $: prefix only when necessary, such as when you need a variable to update in real time or when you’re using complex logic. Otherwise, try to avoid using the $: prefix as much as possible.

10. Be careful when using reactive declarations in loops

When using reactive declarations in loops, the code will be executed multiple times. This can lead to performance issues and unexpected behavior if not done correctly. To avoid this, make sure that you are only declaring variables once outside of the loop and then referencing them inside the loop. Additionally, try to use immutable data structures when possible as they are more efficient than mutable ones. Finally, always test your code thoroughly before deploying it to production.