How to make a "dot function" in javascript

I'd strongly recommend not trying to replace any built-in methods, however, you're free to define your own methods however you like.

You can do this by attaching the method to the Number or String type's prototype:

Number.prototype.foo = function(n) { return this * n; };
String.prototype.bar = function(n) { return this.length * n; };

alert(4..foo(2));  // 8
alert("4".bar(2)); // 2

Further Reading

• Inheritance and the prototype chain

Defining a "dot function" is easy. Here's how you can define it on a single object.

var a = {}, or a = function() {}, or a = [], etc.

a.dotFunction = function() { return 'hi'; }

console.log(a.dotFunction());

If you want to define it on all instances of a "class", use prototype.

function someClass() {
}

someClass.prototype.dotFunction = function() { return 'hi'; };

console.log(new someClass().dotFunction());

You can even do this on built-in types (some, like Prototype.js, do this, though most recommended against it).

Number.prototype.dotFunction = function() { return 'hi'; };

console.log((0).dotFunction());