How can you share code between JavaScript files?

To share code between JavaScript files, you can use modules. In modern JavaScript, you can use ES6 modules with export and import statements. For example, you can export a function from one file and import it into another:

// file1.js
export function greet() {
  console.log("Hello, world!");
}

// file2.js
import { greet } from "./file1.js";
greet();

Alternatively, in Node.js, you can use module.exports and require:

// file1.js
module.exports = function greet() {
  console.log("Hello, world!");
};

// file2.js
const greet = require("./file1.js");
greet();