Why we always require modules at the top of a file? Can we require modules inside of functions?

In Node.js, it is a common practice to require modules at the top of a file for several reasons:

1. Clarity and Organization: Placing all require statements at the top of the file makes it easier to see at a glance which modules the file depends on. This organizational practice enhances readability and maintainability, as all external dependencies are listed in one place.

2. Performance Optimization: When modules are required at the top of the file, they are loaded and cached the first time they are used. Node.js caches the initial loading of modules, so subsequent calls to require() retrieve them from the cache rather than reloading them from the filesystem. This caching mechanism can reduce the load time and overall resource consumption[1][7].

3. Avoiding Duplication: Requiring modules only once at the top of the file prevents redundancy and potential errors from multiple require calls scattered throughout the file. This ensures that each module is loaded and compiled once, regardless of how many times it is used within the file[1][7].

4. Hoisting: In JavaScript, variable and function declarations are hoisted to the top of their containing scope. However, require calls are not hoisted. Placing them at the top prevents issues related to the order of execution and variable availability within the file[1].

Requiring Modules Inside Functions

While it is generally recommended to require modules at the top of a file, there are scenarios where requiring modules inside functions can be beneficial:

1. Conditional Loading: If a module is only needed under certain conditions, requiring it inside a function can save on loading time and memory usage, especially if the condition rarely occurs. This can be particularly useful in functions that handle specific tasks which are not always executed[5][8][9].

2. **Reducing Startu...