Migrating from JS to TS partially throws TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts"

[unknowntester404]

Hello,

I am trying to migrated from JS to TS incrementally. So I've started with two files under constants folder called variables.ts and data.ts
This two files are then used in wdio.conf.js file via import {} from "../constants/variables.ts" for example

However when running yarn test then @wdio/config:ConfigParser: Failed loading configuration file: file:///Users//Projects/**/configs/wdio.conf.js: Unknown file extension ".ts" for /Users//Projects//constants/variables.ts
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for /Users/****/Projects//constants/variables.ts

my tsconfig.json looks like this

{
  "compilerOptions": {
    "target": "ES6",
    "module": "ESNext",
    "moduleResolution": "NodeNext",
    "esModuleInterop": true,
    "types": [
      "node",
      "@wdio/globals/types",
      "@wdio/mocha-framework",
      "@wdio/appium-service"
    ],
    "allowImportingTsExtensions": true,
    "noEmit": true,
    "forceConsistentCasingInFileNames": true
  },
  "include": ["/constants/*.ts"],
  "exclude": [
    "/node_modules",
    "/pages/",
    "/test/",
  ]
}

and my package json has type:"module" inside it.

How can make yarn tests work again? Thank

[christian-bromann]

This two files are then used in wdio.conf.js file via import {} from "../constants/variables.ts" for example

Even though you are importing a .ts file you have to use the .js file extension. Can you try rewriting your import to:

import {} from "../constants/variables.js"

?

[unknowntester404]

This throws

import {VAR1, VAR2, VAR3} from '../constants/variables.js';
^^^^^^

SyntaxError: Cannot use import statement outside a module

[christian-bromann]

This error means that your project uses CJS which requires you to import via const mod = require("mod") instead of import mod from 'mod'. Make sure you set "module": "commonjs", in your tsconfig.json.

[jurjandrei]

Managed to solve this by changing to "target": "ES2016"