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  3. /transpilers

JavaScript Transpilers

Getting Started

Despite its huge growth, JavaScript still has its limitations. For instance, some of the latest language features may not be supported by older browsers and devices, making it difficult for developers to take full advantage of the language's capabilities.

Enter the world of transpilers. A transpiler is a source-to-source compiler that converts code written in one programming language into another while preserving the original code's functionality.

In the case of JavaScript, we can convert modern JavaScript code into a format that can run in older environments that don't support the latest language features.

How Transpilers Work

At a high level, transpilers work by parsing the source code, analyzing its syntax, and then generating equivalent code in the target language. Naturally, the process follows a set of predefined rules and algorithms.

For example, let's take a glance at this ES6 code:

const add = (a, b) => a + b;
console.log(add(2, 3));

A JavaScript transpiler, such as Babel, would convert this code into equivalent code that can run in environments that only support ES5 or earlier versions of JavaScript:

var add = function(a, b) {
  return a + b;
console.log(add(2, 3));

Here, the ES6 arrow function syntax was converted into a traditional function expression, making it compatible with older environments.

Understanding Transpiling and Compiling

When it comes to programming, you can easily get lost in the intricate language. Two related terms you may have already come across are "transpiling" and "compiling".

So, what's the difference?

Compiling is the process of converting a high-level programming language into machine code, which can run directly on a computer's processor.

In contrast, transpiling, is converting code from one high-level language into another. The result is meant to be readable and editable by humans.

Babel — A Common JavaScript Transpiler Choice

Babel is the swiss army knife of modern web development. In today's market, there are a lot of alternatives, but Babel is still a reliable tool for any JavaScript developer who wants to stay ahead of the curve.

One of the key features of Babel is the support of the latest ECMAScript versions. That means we can use newer ES features, such as destructuring and arrow functions, and still have the code run on older browsers and devices.

Now, let's imagine that you're working on a single-page app that needs to display a list of items. You want to use the latest version of JavaScript to make your code as concise and efficient as possible. Here's the code you might write using destructuring and arrow functions:

const items = [{name: 'item1', price: 10}, {name: 'item2', price: 20}];
const displayItems = items.map(({ name, price }) => `${name}: $${price}`);
console.log(displayItems); // ['item1: $10', 'item2: $20']

As we can see, the code is clean, concise, and easy to read. However, it might not work in some environments. To ensure your code is compatible with all technologies, you can use Babel to transpile it into a form that can be understood by older browsers.

The code equivalent transpiled with Babel would look like this:

"use strict";

var items = [{ name: 'item1', price: 10 }, { name: 'item2', price: 20 }];
var displayItems = items.map(function (item) {
  var name = item.name,
      price = item.price;

  return name + ": $" + price;
console.log(displayItems); // ['item1: $10', 'item2: $20']

Final Thoughts

Transpilers open up a world of possibilities that enhance the developer experience and create code bases that are future-proof, efficient, and compatible with older systems.

Key Takeaways:

  • Transpilation allows you to use modern and cutting-edge code features in older environments by converting code written in one language into another.

  • Babel, one of the most popular JavaScript transpilers, achieves this by breaking down code into a structured representation (parsing) and then converting it into code that can be understood by older environments (transformation).

  • By utilizing a transpiler, you can improve the compatibility and performance of your code, allowing you to take advantage of new and evolving language features.

  • Note that transpilation is distinct from compilation, which converts code into a machine-readable format for execution.