Add `*/promises` implementations

[niksy]

https://twitter.com/kikobeats/status/1399440807711723525?s=12

[shellscape]

This one keeps biting us with https://github.com/shellscape/jsx-email

[niksy]

@shellscape which one specifically? Maybe we can start with some implementation and go from there. We only have timers/promises currently.

[shellscape]

fs/promises is the one I get hit by most often. fwiw this is mostly to accommodate users which are importing packages which have these deps, and this gets raised at bundle time.

[niksy]

We can’t really provide anything useful for fs since it can’t really be polyfilled inside browser environment. I think you can alias it to noop in your build process for now.

[shellscape]

that's what I've done. @jspm/core has a complex take on that. subpath exports to noop would also help here

[brianjenkins94]

Some modifications that I made in order to handle arbitrary subpaths:

{
	"name": "node-stdlib-browser-alias",
	"setup": function(build) {
		const builtinsMap = Object.fromEntries(Object.keys(stdLibBrowser).map(function(libName) {
			return [libName, stdLibBrowser[libName]];
		}))

		const filter = new RegExp(`^(${["fs", "path", "url"].join("|")})(/.*)?$`)

		build.onResolve({ "filter": filter }, function(args) {
			if (Object.keys(builtinsMap).some((builtin) => args.path.startsWith(builtin))) {
				return {
					"path": args.path,
					"namespace": "external-global",
					"pluginData": args
				};
			}
		});

		build.onLoad({ "filter": /.*/, "namespace": "external-global" }, async function({ args }) {
			const matches = Object.entries(await import(args["path"])).map(function([key, value]) {
				return `export ${key === "default" ? "default" : `const ${key} =`} ${(typeof value === "function" ? "() => {}" : undefined)};`;
			}).join("\n");

			return {
				"contents": matches,
				"loader": "js"
			};
		});
	}
}