build.mjs

import * as fs from "node:fs";
import * as path from "node:path";
import { fileURLToPath } from "node:url";
import esbuild from "esbuild";

/**
 * @returns {import('esbuild').Plugin}
 */
function patchRecast() {
  return {
    // https://github.com/benjamn/recast/issues/611
    name: "patch-recast",
    setup(build) {
      build.onLoad({ filter: /recast\/lib\/patcher\.js$/ }, async args => {
        let original = await fs.promises.readFile(args.path, "utf8");

        return {
          contents: original
            .replace(
              "var nls = needsLeadingSpace(lines, oldNode.loc, newLines);",
              'var nls = oldNode.type !== "TemplateElement" && needsLeadingSpace(lines, oldNode.loc, newLines);'
            )
            .replace(
              "var nts = needsTrailingSpace(lines, oldNode.loc, newLines)",
              'var nts = oldNode.type !== "TemplateElement" && needsTrailingSpace(lines, oldNode.loc, newLines)'
            )
        };
      });
    }
  };
}

/**
 * @returns {import('esbuild').Plugin}
 */
function patchCjsInterop() {
  return {
    name: "patch-cjs-interop",
    setup(build) {
      build.onEnd(async () => {
        let outfile = "./dist/index.mjs";

        let content = await fs.promises.readFile(outfile);

        // Prepend `createRequire`
        let code = [
          `import {createRequire as __global__createRequire__} from 'module'`,
          `import {dirname as __global__dirname__} from 'path'`,
          `import {fileURLToPath} from 'url'`,

          // CJS interop fixes
          `const require=__global__createRequire__(import.meta.url)`,
          `const __filename=fileURLToPath(import.meta.url)`,
          `const __dirname=__global__dirname__(__filename)`
        ];

        content = `${code.join("\n")}\n${content}`;

        fs.promises.writeFile(outfile, content);
      });
    }
  };
}

const __dirname = path.dirname(fileURLToPath(import.meta.url));

let context = await esbuild.context({
  bundle: true,
  platform: "node",
  target: "node14.21.3",
  external: ["prettier"],
  minify: process.argv.includes("--minify"),
  entryPoints: [path.resolve(__dirname, "./src/index.js")],
  outfile: path.resolve(__dirname, "./dist/index.mjs"),
  format: "esm",
  plugins: [patchRecast(), patchCjsInterop()]
});

await context.rebuild();

if (process.argv.includes("--watch")) {
  await context.watch();
}

await context.dispose();