Functional Programming Ruby vs JavaScript

How is Javascript similar to Ruby in the context of functional programming?

JavaScript and Ruby share some similarities when it comes to functional programming, which include:

  1. First-Class Functions: Both languages treat functions (or methods, in Ruby’s case) as first-class citizens. This means you can assign functions to variables, pass them as arguments to other functions, and return them from functions.

    Example in JavaScript:

    const square = function(x) { return x * x; };
    const result = [1, 2, 3, 4].map(square);  // [1, 4, 9, 16]

    Example in Ruby:

    square = { |x| x ** 2 }
    result = [1, 2, 3, 4].map(&square)  # [1, 4, 9, 16]
  2. Immutable Data: Both languages favor using immutable data, which means that data cannot be changed after it’s created. This helps prevent unexpected side-effects and makes it easier to reason about your code.

  3. Higher-Order Functions: Both languages support the use of higher-order functions, which are functions that can take other functions as arguments and/or return functions as results.

  4. Map, Filter, Reduce: Both JavaScript and Ruby have built-in methods for commonly used operations in functional programming such as map, filter, and reduce (called inject in Ruby).

Despite these similarities, it’s worth noting that JavaScript and Ruby are both multi-paradigm languages that also support object-oriented programming. They offer functional programming features but are not purely functional languages like Haskell or Erlang. Therefore, their approach to functional programming is flexible and can be combined with other programming styles.