Fix builtin loaders with --target=node

[fathyb]

Fixes #969.

Add support for dynamic imports, WebAssembly and Rust with --target=node.

cc @lbguilherme @albizures

• the global modifications on prelude.js are ugly, any suggestion? Maybe make a Node.js prelude and a browser one?

[lbguilherme]

Should resolve to the return of require. resolve(require(__dirname + bundle))

[fathyb]

Are you sure? The original js-loader.js doesn't resolve anything :

parcel/src/builtins/loaders/js-loader.js

Lines 13 to 16 in 0dc062f

	script.onload = function () {
	script.onerror = script.onload = null;
	resolve();
	};

If require is called here it's just to register the __parcel_require so next require calls can require numeric IDs here :

parcel/src/builtins/bundle-loader.js

Lines 27 to 30 in 0dc062f

	return Promise.all(bundles.slice(0, -1).map(loadBundle))
	.then(function () {
	return require(id);
	});

I'm not very familiar with that part though so I may have missed something 😅

[devongovett]

Instead of introducing another global to store the node require function, I just renamed the parcel require function to parcelRequire instead of require so it doesn't conflict with node's require function. This should also fix #761, so that parcel doesn't conflict with the require function exposed by other bundlers or scripts like require.js which might also be on the page. We fall back to checking require if we cannot find the module in parcel's require system.

[devongovett]

would be cool to add support for registering bundle loaders for specific environments. this would allow third party plugins to do the same:

bundler.addBundleLoader('wasm', {
  node: require.resolve('./node/wasm-loader'),
  browser: require.resolve('./browser/wasm-loader')
});

Want to make a followup PR to support that?