Decorators are functions that modify a class, property, method, or method parameter. The following example illustrates how to define and use a simple decorator that adds a static parameter to the class:
// decorator function
function AddMetadata (...args) {
return function (target){
target.metadata = [...args];
}
}
// decorator applied
@AddMetadata({ metadata: 'some values'})
class Model {
}The three dots syntax (...) is the spread operator, which is a feature of JavaScript 2015 that deconstructs the items of a given array.
You might have heard the term annotations; they are simply metadata related to Angular 2. Before the Angular team decided to use TypeScript, they introduced us to a new language that they called AtScript. This language included a feature called annotations, which look exactly like decorators. So what's the difference? The decorator is an interface for creating those Angular annotations. Decorators are executed and in...