https://codepen.io/tkfriend89/full/dVdBrV/
The x^2, sqrt, and % sign are pressed right after a digit.
Ex: Press 9 , then, x^2, you get 89.
% only accepts the range from -1 to 1, and fractions.
Ex: -.1 —> % ------> -10%.
Ex: 8/9 —> % -------> .88898%
What do you guys think?
functionality wise, works great!
Not sure what you mean by % only accepts decimals though. 8/10% returns 80%.
Styling could be a bit better but thats pretty much it. 
I am able to type multiple decimal points with your calculator. For example, I should not be able to enter the following:
…3…0…1
The same goes for x and ÷ and + and - operators. I should not be able to enter multiple consecutive operators of the same type like:
5****9///2–3+4
Also, if you are going to display operators such as ÷ and x, then I think it would look better if those same symbols appeared in the display. Currently, when I click following buttons:
5 x *3 ÷/ 2
I see the following in the display:
5 * 3 / 2
Lastly, the display hides many numbers which are entered or calculated. You should look into displaying such large numbers in scientific e notation.
Thanks, guys. I plan on correcting the code by the end of today.
I appreciate all of the feedback so far!