📦 Understanding ES6 Modules in JavaScript
Category: js / general-concepts
Difficulty: medium
JavaScript applications have grown massively in size and complexity over the years. To manage this growth, developers need tools for organizing code, avoiding global scope pollution, and promoting reusability. Enter the ES6 Module System — a native solution to modular programming in JavaScript. This article explores what ES6 modules are, how they work, and why they're now the standard for modern JavaScript development. 🔍 What Are ES6 Modules? An ES6 Module is a JavaScript file that explicitly exports variables, functions, or classes so they can be imported into other files. They were introduced in ECMAScript 2015 (ES6) and are now supported in all modern browsers and Node.js environments. 🎯 Why Use Modules? Encapsulation: Avoid polluting the global namespace. Reusability: Share logic across files. Maintainability: Organize code by responsibility. Dependency Management: Declare what’s used where. Performance: Modules are statically analyzable (great for bundlers and tree-shaking). 📤 Exporting from a Module There are two types of exports: named and default. Named Exports You can export multiple items from the same module: [code example] Default Export Each module can have one default export: [code example] You can also export a value directly: [code example] 📥 Importing in Other Files Import Named Exports [code example] You can also rename imports: [code example] Import Default Export [code example] Import All (Namespace Import) [code example] 🧪 Combining Named and Default Exports [code example] [code example] ⚙️ Module Characteristics Behavior Variables stay within the module, not global Strict mode by default Module is loaded and run once (shared instance) Static structure import/export must be at the top level of a file Feature CommonJS (require/module.exports) Syntax require() / module.exports Execution Dynamic Top-level only No Tree-shaking ❌ Not supported Standard ❌ Node-specific Mistake Forgetting type="module" in <script> Move to top-level scope Using .js...