How do I make a money system!

Help
#1

Can anyone help me make a money system that you could buy random items (like decorations) by using money (ingame money) which you get from activities like pressing a button or other stuff.
I would also appreciate if you could give some ideas for the mini games!

#2

I thought u where a bit for a sec

#3

What you can do is:

/// default code for first frame
project.money = 0;

/// Coin's update
if (this.hits(player)) {
  project.money += 5;
  this.remove();
}

Tip: If you want to save money, you can use Local Storage! (note: if you open it as an HTML file on the browser, it doesn’t work)

#4

ginormous money bags