§ Monkey patching

Monkey patching is a technique used to extend or modify the behavior of existing objects, functions or methods, in JavaScript. It's often used to add new functionality to built-in objects, without having to inherit from them or modify their prototypes.

Here is an example of monkey patching in JavaScript:

// Monkey patching the built-in Array object
Array.prototype.sum = function() {
  return this.reduce((acc, val) => acc + val, 0);
};

let numbers = [1, 2, 3, 4, 5];
console.log(numbers.sum()); // Output: 15

In this example, the Array object's prototype is being extended by adding a new method sum, which can be called on any Array instance. The new method returns the sum of all elements in the Array by using the reduce method.

We have to mention that such monke-patching is not recommended.