<html><head> <title>Accessor Properties Example</title> <script type="text/javascript"> var book = { _year: 2004, edition: 1 }; //legacy accessor support book.__defineGetter__("year", function(){ return this._year; }); book.__defineSetter__("year", function(newValue){ if (newValue > 2004) { this._year = newValue; this.edition += newValue - 2004; } }); book.year = 2005; alert(book.edition); //2 </script></head><body> <p>Note: this example only works in browsers that have legacy getter/setter support (Firefox, Safari 3, Chrome, Opera 9.5).</p></body></html>