Private variable accessible in node.js prototype-defined function?

Question

Private variable accessible in node.js prototype-defined function?

Consider the following code snippet:

function C1() {
    // private variable in the constructor
    a = 1;
}

C1.prototype.f1 = function() {
console.log( "a=" +  a );
}

C1.prototype.f2 = function() {
    a = 2;
    process.nextTick( this.f1 );
}

o = new C1();
o.f1();
o.f2();

The output observed is:

a=1
a=2

I thought private variables aren't accessible outside of the Constructor function ?

javascript
node.js
asynchronous
private
member

Answer 1

In JavaScript, a variable declared without the "var" keyword has global scope. In the browser this is achieved by attaching the variable to the window object (not sure how it works in Node). If you would like a private variable accessible to your object, try a closure around the object constructor and prototype declaration.