build.ts

/// <reference types='bun-types' />
import { existsSync, rmSync } from "node:fs";
import { join, resolve } from "node:path/posix";

import { transpileDeclaration } from "typescript";
import tsconfig from "../tsconfig.json";

// Constants
const ROOTDIR = resolve(import.meta.dir, "..");
const SOURCEDIR = `${ROOTDIR}/src`;
const OUTDIR = join(ROOTDIR, tsconfig.compilerOptions.declarationDir);

// Remove old content
if (existsSync(OUTDIR)) rmSync(OUTDIR, { recursive: true });

// Transpile files concurrently
const transpiler = new Bun.Transpiler({
  loader: "ts",
  target: "node",

  // Lighter output
  minifyWhitespace: true,
  treeShaking: true,
});

for (const path of new Bun.Glob("**/*.ts").scanSync(SOURCEDIR)) {
  const srcPath = `${SOURCEDIR}/${path}`;

  const pathExtStart = path.lastIndexOf(".");
  const outPathNoExt = `${OUTDIR}/${path.substring(0, pathExtStart >>> 0)}`;

  Bun.file(srcPath)
    .text()
    .then((buf) => {
      const res = transpiler.transformSync(buf);
      if (res.length !== 0) {
        Bun.write(`${outPathNoExt}.js`, res.replace(/const /g, "let "));
      }

      Bun.write(
        `${outPathNoExt}.d.ts`,
        transpileDeclaration(buf, tsconfig as any).outputText
      );
    });
}