Functional typescript

condition_evaluator.ts

 export function and<T>(conditions : Array<(T) => boolean>) : (obj:T) => boolean {
     return (e: T) => conditions.every( c=> c(e));
 }

main.ts

//We want to create an Instance of Video Game Manager and find video games in store base on multiple predicates

import {VideoGame} from "./model/video_game";
import {VideoGameStoreService} from "./services/video_game_store_service";
import {VideoGameManager} from "./services/video_game_manager";
import {VideoGameGenre} from "./enum/video_game_genre";

var videoGameManager = new VideoGameManager(new VideoGameStoreService());
var filtered= videoGameManager.find([ s=> s.Genre === VideoGameGenre.Terror,
                                    s=>s.Pegi>= 18]);

//Output
//[ VideoGame { Name: 'Silent Hill', Genre: 2, Pegi: 18 },
//  VideoGame { Name: 'Resident Evil HD', Genre: 2, Pegi: 18 } ]

video_game_manager.ts

import {VideoGameStoreService} from "../services/video_game_store_service";
import {VideoGame} from "../model/video_game";
import {VideoGameGenre} from "../enum/video_game_genre";
import {and} from "../shared/condition_evaluator";

type Predicate = (v: VideoGame) => boolean;

export class VideoGameManager {

    private videoGameCollection: Array<VideoGame>;


    constructor(private videoGameStoreService: VideoGameStoreService) {
        this.videoGameCollection = videoGameStoreService.getStore();
    }

    getStore(): Array<VideoGame> {
        return this.videoGameCollection;
    }

    inGenre(genre: VideoGameGenre) {
        return this.videoGameCollection.filter(v => v.Genre === genre);
    }

    find(conditions: Predicate[]): Array<VideoGame> {
        return this.videoGameCollection.filter(and(conditions));
    }


}

video_game_store_mock.ts

import {VideoGame} from "../model/video_game";
import {VideoGameGenre} from "../enum/video_game_genre";

export var videoGameCollection : Array<VideoGame> = [
    new VideoGame("Conan", VideoGameGenre.Action, 12),
    new VideoGame("Call of duty Modern Warfare 2", VideoGameGenre.Shooter, 16),
    new VideoGame("Silent Hill", VideoGameGenre.Terror,18),
    new VideoGame("Resident Evil HD", VideoGameGenre.Terror,18)
]

video_game_store_service.ts

import {VideoGame} from "../model/video_game";
import {VideoGameGenre} from "../enum/video_game_genre";
import {videoGameCollection} from "../mock/video_game_store_mock";

export class VideoGameStoreService {

    getStore(): Array<VideoGame> {        
        return videoGameCollection;
    }
}