How do I make my scores work in a game of scissors, paper stone?

I am new to javascript and html. I am trying to make a scissors, paper stone game that the player plays against the computer. However I am not able to get the score to play or get the score to display in html. I have tried adding a rendering function too but doesn’t work. What is wrong with my scoreWindow code? Why does it show as error and null?
Please help.

onClick not working when I attempt to change value of variable

In React, I’m attempting to change the display of 2 elements when certain buttons are clicked on. I either want the title displayed, or an input to edit the title. My title div has a className of a variable named ‘titleDisplay’ with the value of ‘isDisplayed’. I have a function set up to switch it to ‘notDisplayed’