feat: support --config (#38)

* feat: support `--config`

* docs: add `--config` flag

* fix: multiple use of `--config` flag error

README.md

@@ -1,4 +1,5 @@
 # @eslint/create-config
+
 Utility to create ESLint config files
 
 ## <a name="usage"></a>Usage
@@ -15,4 +16,21 @@ npm init @eslint/config
 ```bash
 # use npx
 npx @eslint/create-config
-```
+```
+
+If you want to use the specified shared configs:
+
+```bash
+# use `eslint-config-semistandard` shared config
+npm init @eslint/config --config semistandard
+# or (`eslint-config` prefix is optional)
+npm init @eslint/config --config eslint-config-semistandard
+```
+
+The `--config` flag also supports passing in arrays:
+
+```bash
+npm init @eslint/config --config semistandard,standard
+# or
+npm init @eslint/config --config semistandard --config standard
+```

lib/init/config-initializer.js

@@ -16,6 +16,7 @@ import { Legacy } from "@eslint/eslintrc";
 import { info } from "../shared/logging.js";
 import * as ConfigFile from "./config-file.js";
 import * as npmUtils from "./npm-utils.js";
+import mri from "mri";
 
 const { ConfigOps, naming, ModuleResolver } = Legacy;
 
@@ -571,6 +572,17 @@ function promptUser() {
  *  @returns {void}
  */
 function initializeConfig() {
+    const argv = mri(process.argv.slice(2));
+
+    if (argv.config) {
+        const config = {
+            extends: typeof argv.config === "string" ? argv.config.split(",") : argv.config
+        };
+        const modules = getModulesList(config);
+
+        return askInstallModules(modules).then(() => writeFile(config, "JavaScript"));
+    }
+
     return promptUser();
 }
 

package.json

@@ -50,6 +50,7 @@
         "enquirer": "^2.3.5",
         "js-yaml": "^4.1.0",
         "json-stable-stringify-without-jsonify": "^1.0.1",
+        "mri": "^1.2.0",
         "semver": "^7.2.1"
     },
     "devDependencies": {