Building a Project with Rollup, TypeScript, and Babel for ES5 Compatibility

In the modern web development landscape, developers often use the latest JavaScript (ES6+) and TypeScript features to build robust and maintainable applications. However, not all environments support these modern features. Older devices, such as smart TVs, often rely on outdated JavaScript engines that only support ES5 (ECMAScript 2009). This creates a challenge for developers who need to ensure their applications run smoothly on these devices. In this article, we’ll explore how to build a project using Rollup, TypeScript, and Babel to support ES5, specifically targeting older smart TV environments.

Why Support ES5?

1. Legacy Devices and Smart TVs

Many older smart TVs, gaming consoles, and embedded systems run on browsers with limited JavaScript capabilities. These devices often use outdated browser engines (e.g., WebKit or older versions of Chromium) that only support ES5. Modern JavaScript features like let, const, arrow functions, and Promise are not available in these environments.

For example:

• Samsung Smart TVs (2012–2015): Many of these TVs use the Tizen browser, which has limited ES6+ support.
• LG Smart TVs: Older models use the NetCast or WebOS 1.0–2.0 browsers, which also lack modern JavaScript features.
• Other Devices: Gaming consoles like the PlayStation 3 or Xbox 360, as well as low-end smartphones, often have similar limitations.

If your application targets these devices, failing to support ES5 will result in broken functionality or outright crashes.

2. Wider Audience Reach

By supporting ES5, you ensure that your application can run on a broader range of devices, including older ones. This is especially important for applications like streaming services, which are commonly used on smart TVs. Ignoring ES5 compatibility could alienate a significant portion of your user base.

3. Future-Proofing

While modern devices are becoming more prevalent, older devices are still in use. By building your application with ES5 compatibility in mind, you future-proof it for environments where modern JavaScript is not an option.

How to Build a Project for ES5 Compatibility

To support ES5, we need to use tools that can transpile modern JavaScript (ES6+) and TypeScript into ES5-compatible code. Here’s how to do it using Rollup, TypeScript, and Babel.

Step 1: Set Up the Project

Start by initializing a new project and installing the necessary dependencies.

mkdir my-project
cd my-project
npm init -y

Step 2: Install Dependencies

Install Rollup, TypeScript, Babel, and the required plugins, including core-js for polyfills.

npm install --save-dev rollup @rollup/plugin-babel @rollup/plugin-typescript @rollup/plugin-node-resolve @rollup/plugin-commonjs typescript tslib @babel/core @babel/preset-env @babel/preset-typescript core-js

Step 3: Configure TypeScript

Create a tsconfig.json file to configure TypeScript. This file tells TypeScript to compile your code to ES6 (Babel will handle the ES5 transpilation).

{
  "compilerOptions": {
    "target": "ES6",
    "module": "ESNext",
    "lib": ["DOM", "ES6"],
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "forceConsistentCasingInFileNames": true,
    "outDir": "dist",
    "rootDir": "src"
  },
  "include": ["src/**/*"]
}

Step 4: Configure Babel

Create a .babelrc file to configure Babel. This file tells Babel to transpile your code to ES5 and use core-js for polyfills.

{
  "presets": [
    ["@babel/preset-env", {
      "targets": {
        "browsers": "IE 11" // Target ES5 for older environments
      },
      "useBuiltIns": "usage", // Automatically include required polyfills
      "corejs": 3 // Use core-js version 3
    }],
    "@babel/preset-typescript"
  ]
}

Step 5: Configure Rollup

Create a rollup.config.js file to configure Rollup. This file bundles your code and integrates TypeScript and Babel.

import babel from '@rollup/plugin-babel';
import typescript from '@rollup/plugin-typescript';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';

export default {
  input: 'src/index.ts', // Entry point
  output: {
    file: 'dist/bundle.js', // Output file
    format: 'iife', // Immediately Invoked Function Expression for older environments
    name: 'MyApp', // Global variable name
    sourcemap: true // Generate source maps
  },
  plugins: [
    resolve(), // Resolve third-party modules
    commonjs(), // Convert CommonJS modules to ES6
    typescript(), // Compile TypeScript
    babel({ // Transpile to ES5
      babelHelpers: 'bundled',
      extensions: ['.js', '.jsx', '.ts', '.tsx'],
      exclude: 'node_modules/**'
    })
  ]
};

Step 6: Write Your Code

Create a src directory and add your TypeScript files. For example:

// src/index.ts
const message: string = "Hello, Smart TV!";
console.log(message);

If your code relies on modern features like Promise or fetch, you can include core-js polyfills at the top of your entry file:

import 'core-js/stable'; // Polyfill modern JavaScript features
import 'regenerator-runtime/runtime'; // Polyfill async/await

const message: string = "Hello, Smart TV!";
console.log(message);

Step 7: Build the Project

Run Rollup to bundle and transpile your code.

npx rollup -c

This will generate a dist/bundle.js file that is ES5-compatible and ready for older smart TVs.

Step 8: Test the Output

Test the generated dist/bundle.js file in your target environment (e.g., an older smart TV or an emulator).

Step 9: Optimize for Production

For production, minify the output using a plugin like rollup-plugin-terser:

npm install --save-dev rollup-plugin-terser

Then, update your rollup.config.js:

import { terser } from 'rollup-plugin-terser';

export default {
  // ... other config
  plugins: [
    // ... other plugins
    terser() // Minify the output
  ]
};

Why core-js is Important

Polyfilling Modern Features

Older environments like smart TVs often lack support for modern JavaScript features. For example:

• Promise: Used for asynchronous operations.
• fetch: Used for making network requests.
• Array.prototype.includes: Used for checking if an array contains a specific value.

core-js provides polyfills for these features, ensuring that your application works even in environments where these features are not natively supported.

Conclusion

Supporting ES5 is essential for ensuring compatibility with older devices like smart TVs, which often lack modern JavaScript capabilities. By using Rollup, TypeScript, and Babel, along with core-js for polyfills, you can build applications that are both modern and backward-compatible. This approach not only broadens your audience but also ensures a seamless user experience across a wide range of devices.

Whether you’re building a streaming app, a game, or any other web-based application, following this guide will help you create a robust and inclusive product that works everywhere—even on older smart TVs. Happy coding! 🚀