Immediately Invoked Function Expression
An Immediately Invoked Function Expression (IIFE) is a JavaScript design pattern where a function is defined and executed immediately after its creation. It creates a private scope to avoid polluting the global namespace and can be used to encapsulate code, manage variables, and execute initialization logic. This pattern is commonly employed in modular JavaScript development and for creating closures.
Developers should use IIFEs when they need to isolate code to prevent variable conflicts in the global scope, especially in older JavaScript environments before ES6 modules. It's useful for creating self-contained modules, managing private data, and executing setup code immediately, such as in library initialization or event handler setup. This pattern helps maintain clean, modular code and avoids unintended side-effects from global variables.