Excel JS - SPA clone excel in pure javascript.

In the process of creating this project:

1. Implemented Observer pattern to define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing,
2. Implemented Facade pattern to create a simplified interface for interaction with store and observer;
3. wrote UNIT-tests with using JEST;
4. Implemented a class DOM containing methods for interaction with the DOM tree of the application;

  export function $(selector) {
    return new DOM(selector);
  }

5. Implemented Router - classes required for navigation between application pages;
6. Implemented store, which is an analogue of Redux for working with state;