Targetting ES2015 modules for current browsers not possible (ts:import "name" -> js:import "./name.js")

[urbanhop]

I want to emit javascript with ES2015 modules. My tsconfig is

"target": "es2017",
"module": "es2015",
...

Problem: Typescript expects

import { Component, h, render } from "preact";

In my js files I need however

import { Component, h, render } from "./preact.js";

Maybe might origin from partial browser implementations. At least I could not find any way to work with import "preact" in typesript and emitting import "./preact.js" in js.

Is there a way to get the "./name.js" for into emitted import statements?
If not, are there plans to appraoch the problem?

[ghost]

Duplicate of #4595 -- should already have been fixed by #8895

[urbanhop]

Yes, I work with tsc 2.6.2 and the common case works.

I am actually left with a problem when using the preact library. For preact I hacked a preact.js with exports, such that the browser has an es2015 module. In addition, I use the preact.d.ts file provided by the preact author. For the latter, "./preact.js" does not work.

Could you hint me on how I can deal with that? (now using string-replace on emitted js files, which I would like to get rid of asap)

[ghost]

You could use path mapping.
EDIT: Actually, that' won't work on a relative path -- but you could create a preact.d.ts that symlinks to the one in node_modules.
EDIT: Actually that won't work either, because node_modules/preact/dist/preact.d.ts uses an ambient module declaration declare module "preact". So you'll have to create a local preact.d.ts containing:

import preact = require("preact");
export = preact;

[urbanhop]

Success! Have to figure out the mechanisms going on behind the scenes.

Added suggested preact.d.ts with

import preact = require("preact");
export = preact;

With that in place, import "./preact.js" fails with

error TS2497: Module '".../src/preact"' resolves to a non-module entity and cannot be imported using this construct.

Added a preact.ts with the contents of preact.d.ts .

error TS2306: File '/src/preact.ts' is not a module.

By trials and accident found that the existence of the very same file with any arbitrary name, like p_r_e_act.ts, makes it working! Looks like files are scanned and exhibit effects based on their contents alone. A somewhat mystic but comfortable solution.

Thank you so much for your thoughts and time, very helpful and highly appreciated!

[ghost]

By trials and accident found that the existence of the very same file with any arbitrary name, like p_r_e_act.ts, makes it working! Looks like files are scanned and exhibit effects based on their contents alone. A somewhat mystic but comfortable solution.

That can't be right, are you sure? Can you get a repro?

[ghost]

The resolves to a non-module entity means you should use import preact = require("preact") instead of import * as preact from "preact";.

[urbanhop]

You are right, turns out that my above statements are not correct. Looks like some caching effects disturbed observations. I continue my trials. Thx for the additional input.