Understanding the export = Syntax in TypeScript

The export = syntax is used in TypeScript when you're working with CommonJS or legacy modules that export a single object, function, or class. This syntax allows for compatibility with non-ES module systems where a single value is exported.

Example 1: Exporting a function

function myFunction() {
  console.log("Hello, TypeScript!");
}

export = myFunction;

Here, myFunction is the main export, and using export = allows it to be imported like this in CommonJS:

const myFunction = require("./myModule");
myFunction(); // Hello, TypeScript!

Example 2: Exporting an object

const myObject = {
  name: "TypeScript",
  version: "4.0",
};

export = myObject;

This object can now be imported using:

const myObject = require("./myModule");
console.log(myObject.name); // TypeScript

The export = syntax is mostly used for compatibility with modules that use module.exports in Node.js. For ES6 modules, prefer export default or named exports instead.

Why Wouldn't We Simply Use module.exports?

You don't just use module.exports because TypeScript uses ES module syntax by default. export = bridges the gap between TypeScript’s ES module system and CommonJS modules (module.exports). Without it, TypeScript wouldn’t know how to handle module.exports correctly when working with TypeScript’s module system.