Javscript Functions and privacy

privacy.md

Javascript Functions and privacy

Using Closures

Douglas Crockford’s code conventions for JavaScript recommend this pattern when privacy is important discouraging naming properties with the underscore prefix to indicate privacy.

var Person = (function() {
    function Person(name) {
        this.getName = function() {
            return name;
        };
    }

    return Person;
}());

var p = new Person('John');

print('Person 2 name: ' + p.getName());
// Person 2 name: John

delete p.name;

print('Person 2 name: ' + p.getName() + ' stays private.');
// Person 2 name: John stays private.

Using Symbols

Symbols are ES6 feature See compatibility supports here

var Person = (function() {
    var nameSymbol = Symbol('name');

    function Person(name) {
        this[nameSymbol] = name;
    }

    Person.prototype.getName = function() {
        return this[nameSymbol];
    };

    return Person;
}());

var p = new Person('John');

print('Person 3 name: ' + p.getName());
// Person 3 name: John

delete p.name;

print('Person 3 name: ' + p.getName() + ' — stays private.');
// Person 3 name: John — stays private.

print('Person 3 properties: ' + Object.getOwnPropertyNames(p));
// Person 3 properties: 

Resources

• https://curiosity-driven.org