Hello everyone, I made a basic calculator using react.js (with a lot of help from google) I am currently 15/16 on the test only because I can’t figure out how to add the ability to compute negative numbers.
My project is here
https://codepen.io/Dylanbozarth/pen/vYYKVNX
I know exactly what I need to do, the problem is just doing it.
Thank you in advance
Hello!
I would like to help, but I don’t know how without giving You the answer 
. Besides, even if I gave You my answer, it may not help You because it doesn’t fit your code.
You should try to list the restrictions imposed for the operators, like:
- There can be two operators at max: one any operator or two if one the last one is a minus.
- A operator cannot start the expression, unless it’s the minus.
- The last operator clicked must replace the previous one, unless the last one is a minus.
You should start by trying to add it even if it breaks the calculator. At least that way You can fix every problem You encounter. Make a backup of your working code before!
I also had this thought. Unfortunately in practice I couldn’t get it to work. How would you select the first operator? That’s where I was having trouble.
You don’t need to select the first operator, just don’t add any operator to the start unless it’s a minus (and don’t add more than one).
By the way, You could use the mathjs library so you don’t have to parse the string/expression yourself.
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