Instruction: Define what an Immediately Invoked Function Expression (IIFE) is and provide a use case scenario.
Context: This question tests the candidate's familiarity with JavaScript's function scopes, closures, and the purpose and application of IIFE.
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IIFEs are particularly useful in scenarios where you want to create a private scope for your variables and functions. This is because variables defined within the IIFE cannot be accessed from the outside, thus avoiding potential conflicts with other scripts and preserving the global scope from pollution. They're a cornerstone of the module pattern in JavaScript, especially before the advent of ES6 modules.
One practical use case of an IIFE is when you need to execute some setup code that shouldn't interfere with the global scope. For example, imagine you're working...