Javascript Encapsulation

encaps.js

var obj = function(s) {

    // private member
    v1 = "priv: " + s;    
    
    // public member  
    this.v2 = "pub: " + s;  
    
    // private methods can access private members
    function m1() { 
        return "private method: " + v1;
    }; 
    
    // privileged methods can also access private members
    this.m2 = function() { 
        return "privileged method: " + v1;
    }; 
    
    // privileged methods can call private methods
    this.m3 = function() { 
        return "privileged method: " + m1();
    }; 
    
}

// public methods can access public members
obj.prototype.m4 = function() {
    return "public method: " + this.v2;
}

// public methods can access privileged methods
obj.prototype.m5 = function() {
    return "public method: " + this.m2();
}

var o = new obj("hello");

console.log(o.v1);      // undefined (can't access private members publically)
console.log(o.v2);      // pub: hello
console.log(o.m1());    // TypeError (can't call private methods publically)
console.log(o.m2());    // privileged method: priv: hello
console.log(o.m3());    // privileged method: private method: priv: hello
console.log(o.m4());    // public method: pub: hello
console.log(o.m5());    // public method: privileged method: priv: hello