var Vehicle = new Class({
drive : function() {
console.log("I'm driving a " + this + " with a top speed of " + this.topSpeed);
},
});
var Car = new Class({
Extends : Vehicle,
topSpeed : 250,
initialize : function(make, model) {
this.make = make;
this.model = model;
},
toString : function() {
return this.make + " " + this.model;
},
});
new Car("Fjord", "Taunus").drive();
Then I went on to server-side JavaScript, namely on node.js. There I immediately felt a bit weak without the Class() constructor. I did some googling to see if I could have Mootools on server-side too, but got under the impression that it's not that easy, requiring some customization of Mootools. Hence, I decided to roll my own. And here it is:
function Class(props) {
function copyProperties(from, to) {
for (var key in from) {
to[key] = from[key];
}
}
var constructor = function() {
props.initialize.apply(this, arguments);
};
if (props.Extends) {
copyProperties(props.Extends.prototype, constructor.prototype);
}
copyProperties(props, constructor.prototype);
return constructor;
}
That's not so much code after all, is it? The code in the first snippet actually works with my Class constructor. As you can see, it supports subclassing using 'Extends', a constructor named 'initialize' and any number of methods and properties.
It took me a couple of hours to get these roughly 10 lines of code together though. I had to realise that
- The "class" is actually a constructor function. Hence, the Class() function has to return a constructor
- In any Javascript function, you have an "arguments" array (well not stricly an array but..) that you can use to access all arguments
- You can call any Function using its apply function with the "this" object and a list of arguments
- You can easily copy properties of an object by looping them using "for key in object"
I have to admit that I'm still a bit confused how this all works though :)
Feel free to prove my über-simple class system wrong and point me back to the correct path.
