Support config file in ESM (#13130)

docs/configuration.md

@@ -8,7 +8,9 @@ Prettier uses [cosmiconfig](https://github.com/davidtheclark/cosmiconfig) for co
 - A `"prettier"` key in your `package.json` file.
 - A `.prettierrc` file written in JSON or YAML.
 - A `.prettierrc.json`, `.prettierrc.yml`, `.prettierrc.yaml`, or `.prettierrc.json5` file.
-- A `.prettierrc.js`, `.prettierrc.cjs`, `prettier.config.js`, or `prettier.config.cjs` file that exports an object using `module.exports`.
+- A `.prettierrc.js`, or `prettier.config.js` file that exports an object using `export default` or `module.exports` (depends on the [`type`](https://nodejs.org/api/packages.html#type) value in your `package.json`).
+- A `.prettierrc.mjs`, or `prettier.config.mjs` file that exports an object using `export default`.
+- A `.prettierrc.cjs`, or `prettier.config.cjs` file that exports an object using `module.exports`.
 - A `.prettierrc.toml` file.
 
 The configuration file will be resolved starting from the location of the file being formatted, and searching up the file tree until a config file is (or isn’t) found.
@@ -30,10 +32,22 @@ JSON:
 }
 ```
 
-JS:
+JS(ESM):
 
 ```js
-// prettier.config.js or .prettierrc.js
+// prettier.config.js, .prettierrc.js, prettier.config.mjs, or .prettierrc.mjs
+export default {
+  trailingComma: "es5",
+  tabWidth: 4,
+  semi: false,
+  singleQuote: true,
+};
+```
+
+JS(CommonJS):
+
+```js
+// prettier.config.js, .prettierrc.js, prettier.config.cjs, or .prettierrc.cjs
 module.exports = {
   trailingComma: "es5",
   tabWidth: 4,
@@ -130,8 +144,10 @@ An example configuration repository is available [here](https://github.com/azz/p
 > Note: This method does **not** offer a way to _extend_ the configuration to overwrite some properties from the shared configuration. If you need to do that, import the file in a `.prettierrc.js` file and export the modifications, e.g:
 >
 > ```js
-> module.exports = {
->   ...require("@company/prettier-config"),
+> import companyPrettierConfig from "@company/prettier-config";
+>
+> export default {
+>   ...companyPrettierConfig,
 >   semi: false,
 > };
 > ```