How to chain functions without using prototype?

Question

I have a bunch of useful functions that I have collected during my whole life.

function one(num){
    return num+1;
}

function two(num){
    return num+2;
}

I can call them with two(two(one(5)))

But I would prefer to use (5).one().two().two()

How can I achieve this without using prototype?

I tried to see how underscore chain works, but their code is too intense to understand it

Answer 1

The dot syntax is reserved for objects. So you can do something like

function MyNumber(n) {
    var internal = Number(n);
    this.one = function() {
        internal += 1;
        // here comes the magic that allows chaining:
        return this;
    }
    // this.two analogous
    this.valueOf = function() {
        return internal;
    }
}

new MyNumber(5).one().two().two().valueOf(); // 10

Or you're going to implement these methods on the prototype of the native Number object/function. That would allow (5).one()...