How to run javaScript in lessons

I just started going through the javaScript lessons today, and I’m wondering if there’s a way to run the code to see what it does. For example, I just finished up the counting cards page, and I was missing a necessary space, and I wasn’t able to move on until I found the problem. It took me forever to figure out the problem by going through the code, but had I been able to see what value was returned, it would have been obvious I needed to add the space.

You can use the browser’s console (Ctrl+J in Chrome) and use console.log statements to check values of variables.