From 7ae37941e1f50dea6711696b55fc694ad2e9897c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20T=C3=A1vora?= <joaotavora@gmail.com>
Date: Wed, 21 Jul 2021 13:06:44 +0100
Subject: [PATCH] fix: allow user to add Vitepress configuration to ESM
 packages

If users have a `type: module` entry in their `package.json`, they
could not use VitePress with a `config.js` file.

This change makes it so that `config.cjs` is searched before
`config.js`.  Node's 'require' function allows files with such
extensions to be loaded even from within an ES module project.

* docs/guide/configuration.md: Mention config.cjs

* src/node/config.ts: Consider config.cjs
---
 docs/guide/configuration.md |  5 +++++
 src/node/config.ts          | 25 ++++++++++++-------------
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/docs/guide/configuration.md b/docs/guide/configuration.md
index 7dc8d1e00189..046d7dee879c 100644
--- a/docs/guide/configuration.md
+++ b/docs/guide/configuration.md
@@ -20,4 +20,9 @@ module.exports = {
 }
 ```
 
+::: warning
+If your project uses [ES modules](https://nodejs.org/api/esm.html),
+name this file `.vitepress/config.cjs` instead.
+:::
+
 Check out the [Config Reference](/config/basics) for a full list of options.
diff --git a/src/node/config.ts b/src/node/config.ts
index ec2ff48ab49f..7178aba4eac9 100644
--- a/src/node/config.ts
+++ b/src/node/config.ts
@@ -111,20 +111,19 @@ export async function resolveConfig(
   return config
 }
 
-export async function resolveUserConfig(root: string) {
-  // load user config
-  const configPath = resolve(root, 'config.js')
-  const hasUserConfig = await fs.pathExists(configPath)
-  // always delete cache first before loading config
-  delete require.cache[configPath]
-  const userConfig: UserConfig = hasUserConfig ? require(configPath) : {}
-  if (hasUserConfig) {
-    debug(`loaded config at ${chalk.yellow(configPath)}`)
-  } else {
-    debug(`no config file found.`)
+export async function resolveUserConfig(root: string): Promise<UserConfig> {
+  for (const name of ['config.cjs', 'config.js']) {
+    // load user config
+    const configPath = resolve(root, name)
+    // always delete cache first before loading config
+    delete require.cache[configPath]
+    if (await fs.pathExists(configPath)) {
+      debug(`loaded config at ${chalk.yellow(configPath)}`)
+      return require(configPath)
+    }
   }
-
-  return userConfig
+  debug(`no config file found.`)
+  return {}
 }
 
 export async function resolveSiteData(