This is simply an application of the knowledge gotten over studies in Array, Array methods, Objects, Regex, CSS Grid etc.
The project Basic Calculator is so far my toughest task using Javascript.
The operations of the Calculator were built with its specific function from start. The eval() function and new Function() methods were not used because they pose possible threats.
This project is a work in progress and I will revisit and re-work it to add more features in nearest future.