"If you're using Astro, you should build components with the astro extension".

That was my initial thought when I started using Astro. But after a couple of months building with Astro, my thinking has changed. I no longer build most of my components with astro files.

I mostly use Svelte files instead. This article explains why.

Three reasons

Reason 1: I use Svelte as my framework of choice

This reason is pretty obvious — I have to write Svelte files if I want to use Svelte!

I chose Svelte after evaluating the major three frameworks (React, Vue, and Svelte) and I found that Svelte has a better raw developer experience.

I can share more about why that’s the case, but I’ll have to do that in another blog post since that will be a long one.

Reason 2: the main reason

The main reason is this:

1. Astro can import framework files.
2. But framework files cannot import Astro files

Many commonly used components can be written in Svelte, so it can be imported into both Astro and Svelte files.

Here are some examples:

• A Button component
• An SVG component that searches the project for an SVG icon.

If build these components in Astro, we won’t be able to use them inside Svelte files — and this eventually forced me to rewrite these components in Svelte.

Reason 3: Better syntax

I say better syntax because I find it easier to read Svelte markup over React’s and Vue’s markup — especially when there are if statements or loops.

This might have been because I’ve been using nunjucks for a long time, so the if syntax is much easier for me to read.

Sometimes I choose to write components in Svelte precisely to take advantage of this syntax difference.

When to use Astro files

I only choose the Astro file extension for my component files when I need to use Astro’s API like content collections, which is not available in other frameworks.

What if a component requires both Astro APIs and JavaScript?

I encountered this a couple of times. When this happens, I typically do two things:

• I build an Astro component that retrieves stuff I need with Astro’s API.
• And I build a Svelte component that uses this information.

Usually, I would give both components the same name because it helps me remember that they are directly related to each other.

Wrapping up

Use the following guidelines if you’re deciding which extension when we build components in Astro:

1. Build the component in your framework of choice whenever possible
2. Only use Astro components when you need Astro’s API (or it’s heavily file-system related)

If you need both Astro’s API and JavaScript, feel free to build components with both extensions. Just remember to give them appropriate names so you know they’re related to each other!

By the way, this article is originally written on my blog. Feel free to visit that if you want to have these articles delivered to your email first-hand whenever they're released! 🙂.