What are the differences between closures in Ruby and JavaScript?

What are the differences between closures in Ruby and JavaScript?

Closures in Ruby and JavaScript both allow functions to capture the lexical scope, but they differ in syntax and behavior. In Ruby, closures are typically created using blocks, procs, or lambdas, while JavaScript uses functions. Would you like to know more about how each language implements closures?

Yes, please explain how Ruby handles closures.

In Ruby, closures can be created using blocks, which are chunks of code that can be passed to methods. Procs and lambdas are also used to create closures, with lambdas enforcing stricter argument checking. This allows Ruby to maintain state across method calls.

How about JavaScript? How do closures work there?

In JavaScript, closures are created whenever a function is defined inside another function. The inner function retains access to the outer function's variables even after the outer function has executed. This is a key feature for creating private variables and functions.

Can you give me an example of a closure in both languages?

Sure! In Ruby, you might use a lambda like this: my_lambda = -> { puts 'Hello from closure!' }. In JavaScript, a closure could look like this: function outer() { let count = 0; return function inner() { count++; return count; }; }. Both examples demonstrate how the inner function retains access to the outer function's scope.