Here is a unique version: "Dealing with Node.js ES6 (ESM) Modules in TypeScript can be tricky, especially when the TypeScript Compiler (TSC) fails to emit the

I am facing an issue while transpiling my TypeScript project to JavaScript. I have set the project to resolve as an ES6 Module (ESM) by using the

"module":"ES6"
configuration, but the problem persists.


This is the current setup in my tsconfig.json:
  {
    "compilerOptions": {
      "module": "es6",
      "target": "es6",
      "lib": ["es6"],
      "sourceMap": true,
    }
  }

Test Scenario Involving Two Modules:

I created a basic test scenario with two modules.

  1. The first module — module1.ts — exports only a constant, like so:

    •   export const testText = "It works!"; 
      
  2. The second module — main.ts — simply imports the exported constant from the first module:

    •   import { testText } from 'module1';
        alert(testText);
      

The resulting file for the second module (or main.js) is included in my index.html file, with the type attribute set as type="module" in the <script ...> tag, which looks like this:

    <script src="main.js" type="module"></script>

Testing this setup in Firefox (dom.moduleScripts.enabled enabled) or Chrome Canary (Experimental Web Platform flag enabled) does not yield the expected results.

It appears that the Typescript compiler transpiles the TS

import { testText } from 'module1';
statement into the JS equivalent
import { testText } from 'module1';
. (Both are identical)

The correct ES6 import statement should be:

import { testText } from 'module1.js';
(Note the .js extension) Adding the file extension manually to the generated code makes it work as intended.

Have I made an error in my settings or is there an issue with the Typescript

"module": "es6"
configuration? Is there a way to configure tsc to automatically add .js file extensions to generated import statements?

Answer №1

This is a puzzling decision in TypeScript.

For now, you can navigate around this by explicitly stating the output file:

inside main.ts specify the .js extension and file path:

import { testText } from './module1.js';
alert(testText);

This method will locate module.ts correctly, but it will be saved with the addition of the .js extension.

Also, remember to start local files with ./ since 'bare' module names are reserved for future purposes.

Answer №2

NOTE FROM AUTHOR: "This answer was published on a different date than its original creation due to changes in TypeScript, requiring me to rewrite it twice. Dates are important here to prevent staleness and provide context for referenced technologies."

Written in December 2021

The Fix for the ``es-module-specifier`` Flag in TS, ESM, NODE stacks


Integrating ESM into Node wasn't straightforward, especially when using TypeScript for Node ES-Modules. Initially, it seemed unlikely, but now projects have evolved to support ESM in Node back-end RTE.

Previously, a workaround involved using the flag:

node --es-module-specifier-resolution=node
(Source of solution linked)

This flag served as the best solution until the release of TS 4.7 Nightly.


A Better Solution Emerges


Recent updates include new module & moduleResolution specifiers in the `tsconfig.json`, introduced during the v4.6 nightly builds and transitioned to beta with v4.7 nightly releases. The upcoming v4.7 will officially incorporate these settings.

New specifiers/settings available:
  1. "module": "NodeNext"
  2. "moduleResolution": "NodeNext"
v4.7 announcement with new settings

For optimal functionality, pair these with

"esModuleInterop": true
. This aligns well with ESM implementation and ensures proper operation with node modules.

Here's a template for the ESM `tsconfig.*.json` configuration:

    "compilerOptions": {
        "rootDir": "source",
        "outDir": "build", 
        "lib": ["ESNext"],
        "target": "ES2020",
        "module": "NodeNext",
        "moduleResolution": "NodeNext", 
        "esModuleInterop": true, // Eases ESM support
        "types": ["node"],
        "allowSyntheticDefaultImports": true,
    }

Authored on: May 22nd, 2022 8:50am PST

Adopting module & moduleResolution Specifiers



Varying versions of TS support these configurations: Beta, Nightly, or Latest. Current `typescript@latest` at v4.6 lacks this support.


TS RELEASE VERSION NPM COMMAND TO EXECUTE HAS SUPPORT?
TS Latest v4.6 npm i -D typescript@latest NO
TS Beta v4.7 npm i -D typescript@beta YES
TS Nightly v4.8 npm i -D typescript@next YES

Configure Development Environment for Latest Version

Adjust environment settings for the updated TypeScript version. For VS Code users, ensure appropriate configuration in ./.vscode/settings.json.

  {"typescript.tsdk": "./node_modules/typescript/lib"}

Configuring Runtime Environment

(In this case, Node.js)


Configuration necessity explained:

  • RTE needs explicit instructions beyond just tsconfig.json settings.

**To inform Node about executing an ECMAScript Module instead of CommonJS, utilize either of two methods:

  1. Configure the package.json file via the `"type": "module"` field.
    {
        "name": "project-name",
        "version: "2.4.16",
        "type": "module", 

        // other package.json configurations...
    }
  1. Alternatively, employ the `--input-type “module”` flag along with specific file extensions like `.ets`. This practice clarifies ESM usage.
Example: index file would be named index.ets while TSC emits index.ejs.

Understanding import nuances is crucial for efficient "ES-Module" writing. Key points summarized:

  1. Javascript file extensions required for imports.
  2. ESM imports used URIs, unlike CJS Modules' posix filepaths.
  3. Special characters should be percent-encoded in ESM.
  4. TypeScript doesn’t mandate MimeType prefixes, but they are recommended for clarity.

Best practice example for importing from Node API's & Libraries:

import EventEmitter from 'node:events';

const eEmit = new EventEmitter();

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Can someone guide me on how to organize a div structure into a table format with the help of JQuery

I am new to JQuery and I have created a table using divs instead of the traditional table structure. Each row has the same ids, which I thought would help me sort the table. Here's an example of my code: <div class="column_title">Column 1</ ...

I'm looking to retrieve the selected value from my autocomplete box in React using the Material UI library. How can I

Here is a snippet of code that utilizes an external library called material ui to create a search box with autocomplete functionality. When a value is selected, an input tag is generated with the value "selected value". How can I retrieve this value in ord ...

When a React Router link is activated, the React Bootstrap dropdown remains open instead of closing as expected

<NavDropdown className="userDropdownButton" title="dropdown" id="user-nav-dropdown" alignRight > <div className="userDropDown"> <Link to="/user" className="userDropDownheader"> user </Link> </div> < ...

Steps for managing files in Ionic Native: creating, reading, and writing them

Struggling to find proper examples for file operations like creating, reading, and writing text or logs into a file? I've done a lot of research but haven't stumbled upon any suitable solutions. The examples provided in this link seem helpful, ho ...

Tips for ensuring that functions can pass arguments with uniform overloads

I need to create a function that passes its arguments to another function, both with the same overloads. function original (a: number): boolean; function original (a: string, b: string): boolean; function original (a: number | string, b?: string): boolean ...

Place the retrieved data from the API directly into the editor

I've integrated the LineControl Editor into my app and everything is functioning perfectly, except for when I attempt to insert text into the editor. Here's the link to the LineControl GitHub page: https://github.com/suyati/line-control/wiki Fo ...

How come this variable isn't recognized as 0 even though the debugger is indicating otherwise?

I am currently working on a React component that receives the total number of reviews as a prop. In cases where the number of reviews is 0, I intend to display an element indicating <div>No reviews yet.</div> If there are reviews available, I ...

Unable to download and install jspdf version 1.5.3

Currently, I am facing an issue where I need to convert HTML to PDF using jspdf 1.5.2. However, I am encountering an error that says "Cannot read property 'charAt' of undefined" when trying to utilize html2canvas. When attempting to upgrade to j ...

Using Javascript to update text content by utilizing `innerText` property instead of checking if it is

How can I selectively use Javascript to replace the specific word "Rindan" in the text below, but not if it appears within an attribute such as img alt=="Rindan"? I only want to replace instances of the word "Rindans" when it is part of the inner text an ...

Using jQuery to display items from GitHub API in a custom unordered list format

Attempting to access data from the GitHub API using jQuery (AJAX) and display it on a static webpage. Here are the HTML and JS code snippets: $(document).ready(function(){ $.ajax({ url: 'https://api.github.com/re ...

Vue.js The mp3 files have been successfully added to an array, yet the audio remains silent

While coding, I faced an issue that I resolved by doing some research online and tweaking the sample code. As I added more lines of code, I encountered sections that were a bit confusing to me, but I managed to make them work. My main objective is to devel ...

Issue with Moment.js incorrectly formatting date fields to a day prior to the expected date

Currently, I am attempting to resolve a small issue in my code related to a tiny bug. In my React component, I have set an initial state as follows: const initialFormData = Object.freeze({ date: Moment(new Date()).format('YYYY-MM-DD'), pr ...

Submitting form by clicking a link on the page

To submit a POST request with "amount=1" without displaying it in the URL, I need the site to send this request when any link on the site is clicked. This JavaScript code achieves that with a GET request: window.onload = function () { document.body.oncli ...

What is the best way to apply a hover effect to a specific element?

Within my CSS stylesheet, I've defined the following: li.sort:hover {color: #F00;} All of my list items with the 'sort' class work as intended when the Document Object Model (DOM) is rendered. However, if I dynamically create a brand new ...

Unspecified data response error in Angular JS

As a beginner in Angular JS, I am currently working on calling a Rest API using JSON data. However, when I run the HTTP-server, I am not receiving my response data as expected. function retrieveContacts(contactsdata) { contactsdata.getContacts().the ...

Top tips for writing JavaScript that incorporates an AJAX call to determine whether the default action should be blocked

Utilizing JavaScript and jQuery, I am developing a handler for form submission that will either allow or prevent the form from being submitted based on certain conditions. Although this task is fairly straightforward, it becomes more complex due to the ne ...

Facing difficulties in resetting the time for a countdown in React

I've implemented the react-countdown library to create a timer, but I'm facing an issue with resetting the timer once it reaches zero. The timer should restart again and continue running. Take a look at my code: export default function App() { ...

Having two identical select2 forms on the same page

Integrating two select2 multi-value select boxes into my Rails application is proving to be a challenge. While the top form functions correctly, the bottom one refuses to work as expected. Despite my attempts at changing IDs and adding new JavaScript cod ...

Having trouble with blurriness in the SVG image loading on three.js

Currently, I am using loadTexture (THREE.ImageUtils.loadTexture('/images/areaYellow.svg')) to load SVG images. However, when I zoom in on the image, it becomes blurred. Is there a way to load the image without this blurriness? I am currently work ...

What is the most efficient method for encoding and decoding extensive volumes of data for a JavaScript user?

Currently, I am in the process of developing a standalone Javascript application using Spine and Node.js to create an interactive 'number property' explorer. This application allows users to select any number and discover its various properties s ...