Overview

• It is a sample using TypeScript Decorator.
• Use reflect-metadata to store information defined by Decorator.

System requirements

• Node.js 10.x
• Yarn 1.12.x

Used library

• TypeScript - 3.2.x
• Angular - 7.2.x
• reflect-metadata - 0.1.13

Operation check

1. Download Sample

git clone git@github.com:yasu-s/ts-decorator-sample.git

2. Installing packages

cd ts-decorator-sample
yarn

3. Launch sample application

yarn start

Sample source

src/app/decorators/constants.ts

/** MetaData Key: SampleClassDecorator */
export const METADATE_KEY_SAMPLE_CLASS_DECORATOR = 'SampleClassDecorator';

/** MetaData Key: SamplePropDecorator */
export const METADATE_KEY_SAMPLE_PROP_DECORATOR = 'SamplePropDecorator';

src/app/decorators/sample-class.decorator.ts

import { METADATE_KEY_SAMPLE_CLASS_DECORATOR } from './constants';

export interface SampleClass {
  memo?: string;
}

/** @Annotation */
export const SampleClass = (option?: SampleClass) => {
  return <TFunction extends Function>(target: TFunction) => {
    Reflect.defineMetadata(METADATE_KEY_SAMPLE_CLASS_DECORATOR, option, target);
    return target;
  };
};

src/app/decorators/sample-prop.decorator.ts

import { METADATE_KEY_SAMPLE_PROP_DECORATOR } from './constants';

/** @Annotation */
export const SampleProp = (memo?: string) => {
  return (target: any, propKey: string) => {
    Reflect.defineMetadata(METADATE_KEY_SAMPLE_PROP_DECORATOR, memo, target, propKey);
  };
};

src/app/app.component.ts

import { Component } from '@angular/core';

import { SampleClass } from './decorators/sample-class.decorator';
import { SampleProp } from './decorators/sample-prop.decorator';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css'],
})
@SampleClass({ memo: 'hoge' })
export class AppComponent {
  @SampleProp('hage')
  memo1 = '';
  @SampleProp('hige')
  memo2 = '';
}