Property is a way to define value in a model or in a collection and they convert to an observable so everything that could be done on an observable could be applied to a property. Let's see an example.
Note: Property have advantages over an observable which are described here
Here is the implementation using an observable
var features = blocks.observable([]).extend('filter', function (value) {
return value.type == 'feature';
});
Here is the equivalent when using Property
var App = blocks.Application();
var Project = App.Model({
features: App.Property({
}).extend('filter', function (value) {
return value.type == 'feature';
})
});