Slim down CommonJS runtime code

[marvinhagemeister]

Noticed that esbuild's CommonJS runtime is a bit bigger compared to what tsc generates.

Input:

export const foo = 123;

const bar = 42;
export default bar;

TypeScript tsc --module commonjs --target es2020:

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.foo = void 0;
exports.foo = 123;
const bar = 42;
exports.default = bar;

esbuild:

"use strict";
var __defProp = Object.defineProperty;
var __getOwnPropDesc = Object.getOwnPropertyDescriptor;
var __getOwnPropNames = Object.getOwnPropertyNames;
var __hasOwnProp = Object.prototype.hasOwnProperty;
var __export = (target, all) => {
  for (var name in all)
    __defProp(target, name, { get: all[name], enumerable: true });
};
var __copyProps = (to, from, except, desc) => {
  if (from && typeof from === "object" || typeof from === "function") {
    for (let key of __getOwnPropNames(from))
      if (!__hasOwnProp.call(to, key) && key !== except)
        __defProp(to, key, { get: () => from[key], enumerable: !(desc = __getOwnPropDesc(from, key)) || desc.enumerable });
  }
  return to;
};
var __toCommonJS = (mod) => __copyProps(__defProp({}, "__esModule", { value: true }), mod);

// src/index.ts
var src_exports = {};
__export(src_exports, {
  default: () => src_default,
  foo: () => foo
});
module.exports = __toCommonJS(src_exports);
var foo = 123;
var bar = 42;
var src_default = bar;
// Annotate the CommonJS export names for ESM import in node:
0 && (module.exports = {
  foo
});
//# sourceMappingURL=index.js.map

[lukeed]

Related #1079