Where do built-in methods come from?

Question

I've been studying about JS objects and I faced the description of methods. It says that a method is "a shorthand for a function assigned to the method's name". In other words, a method is a function, right? But the thing is, where do the methods like parseInt() and toLocaleString() come from if I haven't created a function to turn a float-point number into a integer? I googled about built-in functions, but I haven't found any documentation answering this question.

Answer 1

They are built into the js engine, i.e. it does provide the implementation and creates the function (method) in the environment before running any JS code.