Using get method to retrieve singleton instance

singleton_get_static.js

  const localKey = {}
  
  export default class StoreSingleton {
    static _singleton = null

    constructor(key) {
      if (key !== localKey) {
        throw new Error('Use StoreSingleton.get() to get singleton instance instead')
      }
    }
    
    static get() {
      if (StoreSingleton._singleton === null) {
        StoreSingleton._singleton = new StoreSingleton(localKey)
      }
      
      return StoreSingleton._singleton
    }
  }