Since there's no place that I've found to easily copy/paste function signatures whenever I want to implement a decorator, I've composed this repo with code examples and links. All credit goes to this stackoverflow answer.
Note: decorators were implemented in typescript 1.5
Example use: Using the metadata api to store information on a class.
No parameters:
function ClassDecorator(
target: Function // The class the decorator is declared on
) {
console.log("ClassDecorator called on: ", target);
}
@ClassDecorator
class ClassDecoratorExample {
}ClassDecorator called on: function ClassDecoratorExample() {
}
With parameters:
function ClassDecoratorParams(param1: number, param2: string) {
return function(
target: Function // The class the decorator is declared on
) {
console.log("ClassDecoratorParams(" + param1 + ", '" + param2 + "') called on: ", target);
}
}
@ClassDecoratorParams(1, "a")
@ClassDecoratorParams(2, "b")
class ClassDecoratorParamsExample {
}ClassDecoratorParams(2, 'b') called on: function ClassDecoratorParamsExample() {
}
ClassDecoratorParams(1, 'a') called on: function ClassDecoratorParamsExample() {
}
Example use: Creating a @serialize("serializedName") decorator and adding the property name the a list of properties to serialize.
function PropertyDecorator(
target: Object, // The prototype of the class
propertyKey: string | symbol // The name of the property
) {
console.log("PropertyDecorator called on: ", target, propertyKey);
}
class PropertyDecoratorExample {
@PropertyDecorator
name: string;
}PropertyDecorator called on: {} name
function MethodDecorator(
target: Object, // The prototype of the class
propertyKey: string, // The name of the method
descriptor: TypedPropertyDescriptor<any>
) {
console.log("MethodDecorator called on: ", target, propertyKey, descriptor);
}
class MethodDecoratorExample {
@MethodDecorator
method() {
}
}MethodDecorator called on: { method: [Function] } method { value: [Function],
writable: true,
enumerable: true,
configurable: true }
Restrict to a certain function signature:
function TypeRestrictedMethodDecorator(
target: Object, // The prototype of the class
propertyKey: string, // The name of the method
descriptor: TypedPropertyDescriptor<(num: number) => number>
) {
console.log("TypeRestrictedMethodDecorator called on: ", target, propertyKey, descriptor);
}
class TypeRestrictedMethodDecoratorExample {
@TypeRestrictedMethodDecorator
method(num: number): number {
return 0;
}
}TypeRestrictedMethodDecorator called on: { method: [Function] } method { value: [Function],
writable: true,
enumerable: true,
configurable: true }
function StaticMethodDecorator(
target: Function, // the function itself and not the prototype
propertyKey: string | symbol, // The name of the static method
descriptor: TypedPropertyDescriptor<any>
) {
console.log("StaticMethodDecorator called on: ", target, propertyKey, descriptor);
}
class StaticMethodDecoratorExample {
@StaticMethodDecorator
static staticMethod() {
}
}StaticMethodDecorator called on: function StaticMethodDecoratorExample() {
}
function ParameterDecorator(
target: Function, // The prototype of the class
propertyKey: string | symbol, // The name of the method
parameterIndex: number // The index of parameter in the list of the function's parameters
) {
console.log("ParameterDecorator called on: ", target, propertyKey, parameterIndex);
}
class ParameterDecoratorExample {
method(@ParameterDecorator param1: string, @ParameterDecorator param2: number) {
}
}ParameterDecorator called on: { method: [Function] } method 1
ParameterDecorator called on: { method: [Function] } method 0