Using Webpack to turn TypeScript into es5

Question

I've created a really simple environment to experiment with TypeScript and Webpack. I've followed online examples as best I could but the output of the build contains () =>, which should have been changed to ES5 syntax. Note that I'm NOT using Babel - as far as I can tell TypeScript should be able to produce ES5 without it.

Here is part of my package.json:

  "devDependencies": {
    "ts-loader": "8.0.7",
    "typescript": "4.0.3",
    "webpack": "5.2.0",
    "webpack-cli": "4.1.0",
    "webpack-dev-server": "3.11.0"
  },
  "scripts": {
    "build": "webpack"
  },

Here is my tsconfig.json:

{
    "compilerOptions": {
        "outDir": "./dist/",
        "sourceMap": true,
        "noImplicitAny": true,
        "module": "es2020",
        "target": "ES5",
        "allowJs": true
    }
}

Here is the webpack.config.js:

const path = require('path');

module.exports = {
    entry: './src/index.ts',
    devtool: 'inline-source-map',
    module: {
        rules: [
            {
                test: /\.tsx?$/,
                use: 'ts-loader',
                exclude: /node_modules/,
            },
        ],
    },
    resolve: {
        extensions: [ '.tsx', '.ts', '.js' ],
    },
    output: {
        filename: 'my-library.js',
        path: path.resolve(__dirname, 'dist'),
    },
};

Here is src/index.ts:

export const myObj = {
    visual: "the visual",
    audio: "the audio"
}

After I do npm run build I get the following in dist/my-library.js:

(()=>{"use strict";var r={607:(r,e,t)=>{}},e={};function t(o){if(e[o])return e[o].exports;var n=e[o]={exports:{}};return r[o](n,n.exports,t),n.exports}t.d=(r,e)=>{for(var o in e)t.o(e,o)&&!t.o(r,o)&&Object.defineProperty(r,o,{enumerable:!0,get:e[o]})},t.o=(r,e)=>Object.prototype.hasOwnProperty.call(r,e),t(607)})();

Notice that the code won't run on old browsers even though I've specified "ES5".

The folder structure is:

dist
  my-library.js
src
  index.ts
package.json
tsconfig.json
webpack.config.js

What am I missing? Thanks.

Answer 1

You are probably using webpack5 which introduced support for es6+ as the target. The code that you see, is the code that Webpack generates (it's runtime code), you can specify that it should use es5.

// webpack.config.js

const path = require('path');

module.exports = {
    entry: './src/index.ts',
    devtool: 'inline-source-map',
    target: ['web', 'es5']
    // ------ ^
    module: {
        rules: [
            {
                test: /\.tsx?$/,
                use: 'ts-loader',
                exclude: /node_modules/,
            },
        ],
    },
    resolve: {
        extensions: [ '.tsx', '.ts', '.js' ],
    },
    output: {
        filename: 'my-library.js',
        path: path.resolve(__dirname, 'dist'),
    },
};

For more options checkout the docs