How can I make a javascript function which will undo the task of the previous function? [on hold]

Question

I am trying to create a simple React app, but I am having trouble with "undo" functionality.

Example:

1. The current score is shown. Let's say 1000
2. Two buttons increase and decrease respectively Add and Subtract from the score. Let's say by 20 and 40
3. How do I create an undo button that will undo the last action(s)?

This should occur:

• Start => 1000
• Increase => 1020
• Decrease => 980
• Undo => 1020
• Undo => 1000

Answer 1

I guess that you can store the value of the previous score in a variable “preciousScore”. When you click on the undo button it set the score = previousScore