ESM compatibility (#356)

* move config.js files to config.cjs

* update examples

* changeset

* fix lint failure, hopefully

Author: Rich Harris

Diff for: .changeset/stale-plums-heal.md

@@ -0,0 +1,7 @@
+---
+'create-svelte': patch
+'@sveltejs/kit': patch
+'@sveltejs/snowpack-config': patch
+---
+
+Rename _.config.js to _.config.cjs

Diff for: examples/hn.svelte.dev/snowpack.config.js renamed to examples/hn.svelte.dev/snowpack.config.cjs

@@ -16,7 +16,6 @@ npm init svelte@next my-app
 
 > Note: the `@next` is temporary
 
-
 ## Developing
 
 Once you've created a project and installed dependencies with `npm install` (or `pnpm install` or `yarn`), start a development server:
@@ -28,14 +27,13 @@ npm run dev
 npm run dev -- --open
 ```
 
-
 ## Building
 
-Svelte apps are built with *adapters*, which optimise your project for deployment to different environments, like [Begin](https://begin.com), [Netlify](https://www.netlify.com), [Vercel](https://vercel.com) and so on. (You can also create your own adapter — instructions TODO.)
+Svelte apps are built with _adapters_, which optimise your project for deployment to different environments, like [Begin](https://begin.com), [Netlify](https://www.netlify.com), [Vercel](https://vercel.com) and so on. (You can also create your own adapter — instructions TODO.)
 
-By default, `npm run build` will generate a Node app that you can run with `node build`. To use a different adapter, install it and update your `svelte.config.js` accordingly. The following official adapters are available:
+By default, `npm run build` will generate a Node app that you can run with `node build`. To use a different adapter, install it and update your `svelte.config.cjs` accordingly. The following official adapters are available:
 
-* [@sveltejs/adapter-node](https://github.com/sveltejs/kit/tree/master/packages/adapter-node)
-* [@sveltejs/adapter-static](https://github.com/sveltejs/kit/tree/master/packages/adapter-static)
-* [@sveltejs/adapter-netlify](https://github.com/sveltejs/kit/tree/master/packages/adapter-netlify)
-* ...more soon
+- [@sveltejs/adapter-node](https://github.com/sveltejs/kit/tree/master/packages/adapter-node)
+- [@sveltejs/adapter-static](https://github.com/sveltejs/kit/tree/master/packages/adapter-static)
+- [@sveltejs/adapter-netlify](https://github.com/sveltejs/kit/tree/master/packages/adapter-netlify)
+- ...more soon

Diff for: examples/hn.svelte.dev/svelte.config.js renamed to examples/hn.svelte.dev/svelte.config.cjs

@@ -2,4 +2,4 @@
 
 Place to try out [@sveltejs/app](https://github.com/sveltejs/kit). Very basic and incomplete, many things haven't yet been thought through.
 
-To start the app in development mode do `npm run dev`. To build, use `npm run build`. This will use whichever adapter is specified in `svelte.config.js`, which will also need to be installed (or linked).
+To start the app in development mode do `npm run dev`. To build, use `npm run build`. This will use whichever adapter is specified in `svelte.config.cjs`, which will also need to be installed (or linked).

Diff for: examples/realworld.svelte.dev/README.md

@@ -30,10 +30,10 @@ export function update_component(cwd, filepath, replacements) {
 }
 
 /**
- * Adds `svelte-preprocess` to `svelte.config.js`, if there's no preprocessor already.
+ * Adds `svelte-preprocess` to `svelte.config.cjs`, if there's no preprocessor already.
  */
 export function add_svelte_prepocess_to_config(cwd) {
-	const file = path.join(cwd, 'svelte.config.js');
+	const file = path.join(cwd, 'svelte.config.cjs');
 	let config = fs.readFileSync(file, 'utf-8');
 
 	if (config.includes('preprocess:')) {
@@ -56,7 +56,7 @@ export function add_svelte_prepocess_to_config(cwd) {
  * Adds plugin to snowpack config file, if not already present.
  */
 export function add_snowpack_plugin_to_config(cwd, pluginname) {
-	const file = path.join(cwd, 'snowpack.config.js');
+	const file = path.join(cwd, 'snowpack.config.cjs');
 	let config = fs.readFileSync(file, 'utf-8');
 
 	if (config.includes(pluginname)) {

Diff for: examples/realworld.svelte.dev/snowpack.config.js renamed to examples/realworld.svelte.dev/snowpack.config.cjs

@@ -31,7 +31,7 @@ npm run dev -- --open
 
 Svelte apps are built with _adapters_, which optimise your project for deployment to different environments, like [Begin](https://begin.com), [Netlify](https://www.netlify.com), [Vercel](https://vercel.com) and so on. (You can also create your own adapter — instructions TODO.)
 
-By default, `npm run build` will generate a Node app that you can run with `node build`. To use a different adapter, install it and update your `svelte.config.js` accordingly. The following official adapters are available:
+By default, `npm run build` will generate a Node app that you can run with `node build`. To use a different adapter, install it and update your `svelte.config.cjs` accordingly. The following official adapters are available:
 
 - [@sveltejs/adapter-node](https://github.com/sveltejs/kit/tree/master/packages/adapter-node)
 - [@sveltejs/adapter-static](https://github.com/sveltejs/kit/tree/master/packages/adapter-static)

Diff for: examples/realworld.svelte.dev/svelte.config.js renamed to examples/realworld.svelte.dev/svelte.config.cjs

@@ -11,5 +11,6 @@
 		"@sveltejs/kit": "workspace:*",
 		"@sveltejs/snowpack-config": "workspace:*",
 		"svelte": "^3.29.0"
-	}
+	},
+	"type": "module"
 }