Dear all,
I am new to javascript.I have a little doubt in basic concepts in javascript.

//Example Program
class classname(){


//Decalaring Properties
    var length;
    var abcd;


    public function toUpperCase(){
//This Method is used to convert the strings into uppercase
    }

    public function toLowerCase(){
//This Method is used to convert the strings into LowerCase
    }

}

Point 1:

Methods are the actions that can be performed on objects.
var str="Hello world!";
document.write(str.toUpperCase());

Point 2:
property is like variable (can able to set and get value at runtime.)

I want to know how built-in-properties in javascript works?
How "length" property works in javascript.?

Thank you,

Regards,
Prem

(the code you've sent is not javascript)
all methods are functions, properties may also be functions. In case of length, -it's not a property, it's a value which (in in turn, and in fact) is a result of (an internally) self-triggered function.