Question

First, my experience with JavaScript is limited to web development and a little self-study. I want to understand the point of having private members in JavaScript. Take an example,

var myObject = {
    WriteWord: function() {
        var secret = 'word';
        document.writeln(secret);  
    }
};

myObject.WriteWord();

Private variable secret cannot be seen by the caller. AFAIK, I can notify potential callers of the existence of WriteWord in a few ways:

1. Document the code. Like jQuery does.
2. For .NET guys, write a custom visual studio intellisense plugin.
3. Read the code directly.

Now let’s say I minify and even obfuscate the code. Its now unreadable. In my mind, given this scenerio, a lack of documentation is just as good as a private variable.

Is this scenerio uncommon or somehow wrong? What is the importance of private variables in JavaScript?

Answer 1

Scoping variables carefully in JavaScript eliminates the possibility of another script on your page clobbering a variable.

This becomes a valid concern when working with many different JavaScript libraries/files from possibly many different programmers.