Yousif's Calculator

Hi Yousif. Thanks for sending in your calculator. I'm putting on my hat as HYF mentor in judging your work. I warn you that you may not like what I'm about to say.

I have cloned your repo, typed yarn install and yarn start and am looking at the screen that appears.

About the calculator itself

• This is not the scientific RPN calculator I asked for. It looks like a traditional, algebraic calculator with some very limited scientific functions. How can I compute the Rydberg constant with this calculator? How do I enter a real number with exponential notation, like the mass of an electron (9.10938356e-31 kilograms). There is no key to enter a decimal or a way to enter the exponential part of a real number.

  If this was an assignment from a potential employer to decide whether to hire you I'm afraid you wouldn't get the job. ("Yeah, real clever guy, but doesn't do what you ask him to do.")

• Part of the assignment is to do research into an existing product to discover how it works and to reverse-engineer it. So it's not just about coding.

• When I start up the app I am immediately confronted with warnings:

  ./src/App.js
  Line 3:  'isCompilable' is defined but never used        no-unused-vars
  Line 3:  'isBracketBalanced' is defined but never used   no-unused-vars
  Line 3:  'isOperatorBalanced' is defined but never used  no-unused-vars
  ./src/util/calcUtil.js
  Line 98:   Expected an object to be thrown   no-throw-literal
  Line 244:  'node' is defined but never used  no-unused-vars
  Line 251:  Expected an object to be thrown   no-throw-literal
  Line 258:  Expected an object to be thrown   no-throw-literal
  Line 266:  Expected an object to be thrown   no-throw-literal
  

  The fact that these warnings are here signals to me that you were in great haste to deliver this result. I would have preferred for you to take more time to remove the warnings (putting aside the issue that this is not the calculator I asked for in the first place).

• I'm at a loss how to operate this calculator. What does the () button do? What is Filter?

The Source Code

• Your repo is missing a .gitignore file (e.g. excluding the node_modules folder). In VSCode I immediately get a warning that there are too many files to track.

• I have a spelling checker enabled in VSCode (see my VSCode Tips) and several spelling errors are highlighted when I open up App.js, e.g. clearPannel -> clearPanel, filterd -> filtered. You may think 'nitpicking' but I think 'sloppy'.

• More seriously is the misspelling of calssName which should be className. Because of this any styling depending on the class name will fail.

• What do you mean with the prefix ptn? Did you mean btn for button?

• You are making heavy use of refs. But this is actively discouraged "Avoid using refs for anything that can be done declaratively." See Refs and the DOM.

• In calcUtil.js the spelling checker flags Faild in line 266. I wonder what 'failed' here. Again, these are silly spelling mistakes that you should try and avoid.

• I've not further examined the code in calcUtil.js. I'm sure you've done clever things and had a lot of fun, but the end result is something completely different than was asked for.

Closing thoughts

Yousif, I may have been a bit harsh in my comments, but is important that you understand that being a professional developer is not about doing clever things in the shortest amount of time possible, it is about painstakingly meeting (or exceeding) your customer's requirements.

Perhaps you want to rethink the project and try and build the RPN calculator that was asked for. If you do, make sure that I can compute the Rydberg constant with it. If you've done that and found it too easy then, for instance, extend the calculator with programmability like found in the HP 25. Of course, if I haven't completely turned you off and you still have time.

Best wishes,
Jim