Instruction: Describe techniques to avoid or mitigate callback hell in Node.js.
Context: This question evaluates the candidate's ability to write clean, maintainable Node.js code by avoiding or mitigating callback hell, which can lead to deeply nested callbacks.
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To begin with, callback hell, also known as "Pyramid of Doom," is a situation where callbacks are nested within callbacks several levels deep, making the code hard to read, understand, and maintain. This often arises in complex asynchronous operations, which are commonplace in Node.js applications due to its non-blocking I/O model.
One effective strategy to avoid callback hell is the use of Promises. Promises represent the future result of an asynchronous operation, allowing us to chain .then() methods for sequential operations or .catch() for error handling in a much cleaner and more readable way than nested callbacks. This not only improves code readability but also makes error handling...