What is the difference between first-class functions and higher-order functions?

What is the difference between first-class functions and higher-order functions?

First-class functions are functions that can be treated like any other variable. They can be assigned to variables, passed as arguments, or returned from other functions. Higher-order functions, on the other hand, are functions that take other functions as arguments or return them as results.

Can you give me an example of a higher-order function?

Sure! A common example is the map function in JavaScript, which takes a function as an argument and applies it to each element in an array, returning a new array.

What about first-class functions? Can you show me an example?

Absolutely! In JavaScript, you can assign a function to a variable like this: const greet = function() { return 'Hello!'; }. Here, greet is a first-class function.

Are all higher-order functions also first-class functions?

Yes, all higher-order functions are first-class functions because they can accept or return other functions, but not all first-class functions are higher-order functions.