[TS] Polymorphism + Generic Type + Interface

// Storage는 이미 JS내 존재하여 재선언이 됨
interface SStorage<T> {
	[key:string]: T
}

class LocalStorage<T> {
	// 초기화할 것이 없기 때문에 constructor 사용하지 않음 
	private storage: SStorage<T> = {}
    
    set(key: string, value: T) {
    	if (this.storage[key] === undefined) {
	    	this.storage[key] = value    
        }
    }
    get(key: string): T {
    	if (this.storage[key] !== undefined) {
	    	return this.storage[key]
        }
    }
    remove(key: string) {
    	if (this.storage[key] === undefined) {
	    	delete this.storage[key]
        }
    }
    clear() {
    	this.storage = {}
    }
}

const stringsStorage = new LocalStorage<string>()
stringsStorage.get("key") // return string
stringsStorage.set("hello", "hi") // value: string

const booleansStorage = new LocalStorage<boolean>()
booleansStroage.get("xxx") // return boolean
boolenasStroage.set("xxx", true) // value: boolean