Today I saw a JavaScript syntax (when invoking a function) that is unfamiliar to me. It was like:
def('Person') ({
init: function(name) {this.name=name;}
,speak: function(text) {alert(text || 'Hi, my name is ' + this.name);}
});
, and
def('Ninja') << Person ({
kick: function() {this.speak('I kick u!');}
});
1: What happens with the object within the parentheses in the first example? It is handled by the def
function somehow, but I don't understand what is going on here (see the def
function below). Where does the object go?
2: About the same thing again, but a use of the <<
operator that I never seen (I think!). What's that all about?
The code is from http://gist.github.com/474994, where Joe Dalton has made a small JavaScript-OO-inheritance thing (it is apparently a fork of someone else's work, but quite thoroughly rewritten, as it seems). Maybe you want to check it out there for the stuff referenced by the def
function, which I give you here:
function def(klassName, context) {
context || (context = global);
// Create class on given context (defaults to global object)
var Klass =
context[klassName] = function Klass() {
// Called as a constructor
if (this != context) {
// Allow the init method to return a different class/object
return this.init && this.init.apply(this, arguments);
}
// Called as a method
// defer setup of superclass and plugins
deferred._super = Klass;
deferred._plugins = arguments[0] || { };
};
// Add static helper method
Klass.addPlugins = addPlugins;
// Called as function when not
// inheriting from a superclass
deferred = function(plugins) {
return Klass.addPlugins(plugins);
};
// valueOf is called to set up
// inheritance from a superclass
deferred.valueOf = function() {
var Superclass = deferred._super;
if (!Superclass)
return Klass;
Subclass.prototype = Superclass.prototype;
Klass.prototype = new Subclass;
Klass.superclass = Superclass;
Klass.prototype.constructor = Klass;
return Klass.addPlugins(deferred._plugins);
};
return deferred;
}
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