Deno: Native support for loading ES Modules

Created on 12 Oct 2018 · 5Comments · Source: denoland/deno

Currently Deno cannot load JavaScript that requires ES import statements natively. It supports it in TypeScript by transpiling the module to AMD and then loading it.

Both Node.js and d8 support this, so there are examples in place.

Adding this for tracking purposes as this is likely something I will work on in the future (e.g. this is fairly complex problem to tackle and not for the weak of heart).

Source

kitsonk

👍15

Most helpful comment

I’m working on this
WIP here https://github.com/ry/deno/tree/esm

ry on 6 Dec 2018

🎉2 👍2

All 5 comments

Why did I think this was an issue? Mostly because I never tried it I guess. I just assumed that TypeScript wouldn't transpile JS files, but it does. So currently Deno will take something like this:

foo.js

import * as bar from "./bar.js";

(async () => {
  const baz = await import("./baz.ts");
  console.log(baz);
})();

export const foo = "bar";

console.log(bar);

And transform it to:

define(["require", "exports", "./bar.js"], function (require, exports, bar) {
    "use strict";
    Object.defineProperty(exports, "__esModule", { value: true });
    (async () => {
        const baz = await new Promise((resolve_1, reject_1) => { require(["./baz.ts"], resolve_1, reject_1);});
        console.log(baz);
    })();
    exports.foo = "bar";
    console.log(bar);
});
//# sourceMappingURL=data:application/json;base64,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

Which loads perfectly with the Deno compiler and stack traces will map back to the source JavaScript file. I have an example available at kitsonk/deno_example.

So coupled with #1068 end users can fully author ES Modules in plain JavaScript, with type safety and even interpolate TypeScript and JavaScript modules. That significantly lowers the priority of this issue in my mind. There _may_ be advantages to moving over to ES Modules from AMD, but the complication of integrating to V8 is rather daunting.

cc: @sebs

kitsonk on 23 Oct 2018

Thanks for linking me ;) <3 Its a well received feature where I stand.