Javascript Inheritance

function extendClass(subClass, superClass){
    function F(){};
    F.prototype = superClass.prototype;
    subClass.prototype = new F();
    subClass.prototype.constructor = subClass;
 
    subClass.superClass = superClass.prototype;
    if(superClass.prototype.constructor == Object.prototype.constructor) {
        superClass.prototype.constructor = superClass;
    }
    
    // insert call to superClass constructor
    var constructorStr = subClass.prototype.constructor + ""; // convert to string
    var splitAt = constructorStr.indexOf('{') + 1;
    var start = constructorStr.substring(0, splitAt);
    var end = constructorStr.substring(splitAt, constructorStr.length);
 
    var newMethod = "arguments.callee.superClass.constructor.call(this);";
 
    var newConstructor = start + newMethod + end;
 
    subClass.prototype.constructor = eval(newConstructor);
}
 
 
// ------------- BEGIN BaseObject ------------- //
function BaseObject() {
}
 
BaseObject.prototype.method = function() {
    alert("Alert from BaseObject.method");
}
 
// ------------- END BaseObject ------------- //
 
// ------------- BEGIN InheritsBaseObject ------------- //
function InheritsBaseObject() {
}
extendClass(InheritsBaseObject, BaseObject);
 
InheritsBaseObject.prototype.method = function() {
    alert('I overrode BaseObject.method.');
}
// ------------- END InheritsBaseObject ------------- //
 
var x = new InheritsBaseObject();
x.method();