Create custom function in prototype of Boolean that return self value in Integer

Question

I want to create a custom prototype that convert the self boolean to integer

example

let x = true;
x.toInt() // 1

I tried to create a custom prototype but I can't find the value

Boolean.prototype.testf=() => {console.log(this)}; // don't found value of true

Answer 1

You cant use arrow functions as they determine their this lexically, go with a regular function:

 Boolean.prototype.toInt = function() {
   return +this;
 };