Babel targets don't recognize Node.js 16

[nicolo-ribaudo]

Discussed in #13912

Why does Babel transpile async functions to generators via _asyncToGenerator if target supports async/await?

^{Originally posted by nlucero November 1, 2021}
I'm trying to understand why my transpiled code transforms regular async functions to generators via _asyncToGenerator if the compilation target already supports async functions.

I'm using @babel/preset-env and targeting node >=16.0.0 via targets. This is my config file:

module.exports = {
  presets: [
    [
      '@babel/preset-env',
      {
        targets: {
          browsers: `node >=16.0.0`,
        },
      },
    ],
  ],
  plugins: [
    ['@babel/plugin-proposal-decorators', { legacy: true }],
    ['@babel/plugin-proposal-private-methods', { loose: true }],
    ['@babel/plugin-proposal-class-properties', { loose: true }],
    [
      'module-resolver',
      {
        root: ['./src'],
      },
    ],
  ],
}

If I inspect my transpiled code, I see my async functions are transpiled to something like this:

var login = /*#__PURE__*/function () {
  var _ref = _asyncToGenerator( /*#__PURE__*/regeneratorRuntime.mark(function _callee(req, res) {
    var _req$body, username, password, token, name, cookieConfig;

    return regeneratorRuntime.wrap(function _callee$(_context) {
      // Implementation here
    }, _callee);
  }));

  return function login(_x, _x2) {
    return _ref.apply(this, arguments);
  };
}();

This seems unnecessary to me since my transpilation target (node v16.x.x) fully supports async functions. Is there a good reason why this is being done this way? Could it be a misconfiguration on my end?

For more context, the transpiled code uses native async functions (no _asyncToGenerator whatsoever) if I set my target to node>=14.0.0, so this might be a regression introduced recently.

[nicolo-ribaudo]

When targeting node 16.0.0, Babel complains that it's not a known Node.js version. When targeting node >=14.0.0, Babel doesn't transpile async functions.

[nicolo-ribaudo]

Oh thanks @JLHwung; the reason is #13912 (comment).