CODEWITHSUNDEEP
javascriptnode.jstypescriptwebpackbabeljs
Mateusz Jagiełło
Mateusz Jagiełło

Reputation: 7144

Simple library with babel, typescript and webpack - TypeError: (...) is not a function; at Object.<anonymous>

So 3 days ago I hit weird problem with bundling simple function with babel, typescript and webpack.

Whole "not working" example is available at https://codesandbox.io/s/zen-wright-y3vql. You just need download, npm/yarn install, npm/yarn run build and node test-run.js.

I have just few simple files.

export const sum = (a: number, b: number) => a + b;

{
  "name": "babel-test",
  "version": "1.0.0",
  "main": "dist/index.js",
  "scripts": {
    "dev": "webpack",
    "build": "NODE_ENV=production webpack"
  },
  "dependencies": {},
  "devDependencies": {
    "@babel/core": "^7.10.4",
    "@babel/preset-env": "^7.10.4",
    "@babel/preset-typescript": "^7.10.4",
    "@types/node": "^14.0.23",
    "@types/webpack": "^4.41.21",
    "babel-loader": "^8.1.0",
    "ts-node": "^8.10.2",
    "typescript": "^3.9.6",
    "webpack": "^4.43.0",
    "webpack-cli": "^3.3.12"
  }
}


{
  "presets": [
    "@babel/preset-env",
    "@babel/preset-typescript"
  ]
}

{
  "compilerOptions": {
    "module": "commonjs",
    "jsx": "preserve",
    "esModuleInterop": true,
    "sourceMap": true,
    "allowJs": true,
    "lib": [
      "es6",
      "dom"
    ],
    "rootDir": "src",
    "moduleResolution": "node"
  }
}

import path from "path";
import webpack from "webpack";

const isProduction = process.env.NODE_ENV === "production";
const isDevelopment = !isProduction;

const config: webpack.Configuration = {
  mode: isProduction ? "production" : "development",
  entry: "./src/index.ts",
  watch: isDevelopment,

  output: {
    filename: "index.js",
    path: path.resolve(__dirname, "dist/"),
  },

  module: {
    rules: [
      {
        test: /\.(js|ts)$/,
        exclude: [/node_modules/],
        loader: "babel-loader",
      },
    ],
  }
};

export default config;

const sum = require("./dist/index.js");

console.log(sum);
sum(1, 2);

And, after build it with webpack or npm run build and run with node test-run.js I have this error:

/Users/sigo/Downloads/hife9/test-run.js:4
sum(1, 2);
^

TypeError: sum is not a function
    at Object.<anonymous> (/Users/sigo/Downloads/hife9/test-run.js:4:1)
    at Module._compile (internal/modules/cjs/loader.js:1201:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1221:10)
    at Module.load (internal/modules/cjs/loader.js:1050:32)
    at Function.Module._load (internal/modules/cjs/loader.js:938:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at internal/main/run_main_module.js:17:47

I've tried tricks with core-js and transform runtime/regenerator things without result.

Upvotes: 1

Views: 544

Answers (1)

sdgluck
sdgluck

Reputation: 27257

You have sum as a named export, but you importing it as if it were the default export.

Read about the difference on MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/export.

It should be imported like so:

const { sum } = require("./dist/index.js");

console.log(sum);
sum(1, 2);

Here is an updated CodeSandbox to demonstrate: https://codesandbox.io/s/serene-gould-1xnw7

(I made various other changes to your CodeSandbox, as it did not work as-is.)

Upvotes: 1

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