Really fix issue with detecting AMD-like imports

[seishun]

#4009 fixed it for TypeScript, but the same detection can be performed on JavaScript.

[kitsonk]

We want/need it in JavaScript, as there are situations where we are transpiling from AMD to ESM using the compiler, as mentioned in the PR.

[seishun]

Do such situations currently exist or is it pure theory?

[kitsonk]

They exist.

[seishun]

Please provide an example.

[kitsonk]

The only time JavaScript source files are created in the compiler is when checkJs is true in a TSConfig. When that is the case, the following would be converted to ESM:

define(["./foo.ts"], function (foo) {
  console.log(foo);
});

would emit as something like:

import * as foo from "./foo.ts";
console.log(foo);

The same applies for CommonJS modules:

const foo = require("./foo.ts");
console.log(foo);

I know this because I wrote the code, so it isn't speculation on my part. It is an intentional feature. The reason why there is an option in the TypeScript preprocess is specifically for this transpilation feature as well.

[seishun]

Could you provide more specific steps? I ran your CommonJS example in a directory with the following tsconfig.json:

{
  "compilerOptions": {
    "checkJs": true,
    "allowJs": true
  }
}

It didn't seem to be converted to ESM:

C:\Users\Nikolai\test-proj-delete>..\deno\target\debug\deno.exe test.js
error: Uncaught ReferenceError: require is not defined
► file:///C:/Users/Nikolai/test-proj-delete/test.js:1:13

1 const foo = require("./foo.ts");
              ^

    at file:///C:/Users/Nikolai/test-proj-delete/test.js:1:13

[kitsonk]

You need to pass the tsconfig.json as an argument to Deno. It does not automatically detect it.

[seishun]

C:\Users\Nikolai\test-proj-delete>..\deno\target\debug\deno.exe --config tsconfig.json test.js
error: Uncaught ReferenceError: require is not defined
► file:///C:/Users/Nikolai/test-proj-delete/test.js:1:13

1 const foo = require("./foo.ts");
              ^

    at file:///C:/Users/Nikolai/test-proj-delete/test.js:1:13

Do you get a different result?

[ry]

This was addressed by @kitsonk in another way in 6431622

[seishun]

The issue is still there if checkJs is enabled.

tsconfig.json

{
  "compilerOptions": {
    "checkJs": true,
    "allowJs": true
  }
}

foo.ts

import "./test.js";

test.js

function define(foo) {}
define(["long"]);

..\deno\target\debug\deno.exe --config tsconfig.json foo.ts

Compile file:///C:/Users/Nikolai/test-proj-delete/foo.ts
error: Uncaught URIError: relative import path "long" not prefixed with / or ./ or ../ Imported from "file:///C:/Users/Nikolai/test-proj-delete/test.js"

[ry]

I've opened #4110 with your report. Let's move the discussion there.