base-configs-eslint/scripts/postinstall.cjs

"use strict";

/* eslint no-console: "off", n/no-process-exit: "off" -- CLI app that gives users feedback */

const fs = require("node:fs");
const path = require("node:path");
const process = require("node:process");
const checkConfig = require("@ivuorinen/config-checker");
const foundConfig = checkConfig("eslint");

if (foundConfig.length > 0) {
  console.log("eslint-config: Found existing eslint config file, skipping creation.");
  console.log("eslint-config: If you want to create a new config file, please remove the existing one.");
  console.log(`eslint-config: Found config files at: ${foundConfig.join(", ")}`);
  process.exit(0);
}

const filePath = path.join(process.env.INIT_CWD, "eslint.config.mjs");
const fileConfig = `import ivuorinenConfig from '@ivuorinen/eslint-config';

export default [
  ...ivuorinenConfig,

  // your modifications
  {
    rules: {
      // "no-unused-vars": "warn"
    }
  }
];
`;

if (!fs.existsSync(filePath)) {
  fs.writeFileSync(filePath, fileConfig);
}