To make the function pure, it should return the fetched data directly without relying on external state or global variables. Introducing a callback or using global variables can introduce side effects, which contradicts the principles of pure functions.

ES6 object literals allow the use of computed property names, which is particularly beneficial in scenarios where dynamic property names are based on user input. Computed property names enable the creation of object properties dynamically based on expressions, providing flexibility and conciseness in handling user input.

When using await inside a loop, such as a while loop, it may lead to unexpected behavior. This is because the loop will not pause for each asynchronous operation to complete before moving to the next iteration, potentially causing them to run sequentially. It's crucial to understand the implications of using await inside loops and consider alternative approaches for parallel execution of asynchronous operations.

To use destructuring in a for...of loop iterating over a Map, you would write for (const [key, value] of map). The value here is the second element of the destructuring assignment, representing the value associated with the current key in the Map.

To import a default export from an ES6 module, you use the import keyword followed by any name of your choice, as the default export does not have a specific name. The imported name serves as an alias for the default export in your code.

Decorators in JavaScript are higher-order functions that alter the behavior or execution context of another function. They are often used to add functionalities to functions or methods.

When exporting a class or function as a default export, you can simply use export default followed by the class or function declaration without explicitly using the function or class keywords.

When a generator function encounters a yield keyword, it pauses the execution of the function, preserving its state. The function can later be resumed from the last yield encountered, allowing for efficient iteration over a sequence of values.

Functional composition applies functions from right to left, so compose(f, g) means applying f after g. Therefore, the result is equivalent to f(g(x)).

Yes, the spread operator can be used to combine two arrays into one by spreading the elements of both arrays into a new array. It's a concise way of merging arrays without modifying the original arrays.