Stop the timer when the test is done

- [Narrator] Our typing speed tester doesn't really have any practical purpose unless the clock stops when the test is done. And right now, that doesn't happen. It just keep running. To stop the clock, we first need to remember why the clock is running to begin with. That's happening here inside the start function. We set an interval to a thousandth of a second, and then we run the run timer function every thousandth of a second, and then we increment up and the clock is running. So to stop the clock, we need to somehow stop this interval.

The problem is, we need to do that from outside the start function and we can't because we have no way of referring to the interval to begin with, so if we try to stop it, we'll just stop some other interval that's running and nothing will work. The good news is this is relatively easy to solve, and we addressed the solution previously when we talked about functions. Let me show you what I mean. If I go up to the top here and set up a new global variable called interval, then scroll down, and put set interval inside that variable, this variable now effectively is the set interval function.

That means, if I used a clear interval function on interval, I am in fact using it on set interval and we clear this interval. Scroll up to spell check. Here we have the conditional statement that tests whether text entered in this box equals origin text in this box, and when it's true, I clear interval, interval. Now clear interval is passed down to interval, and interval is clear, and the clock stops.

Save it, and go test it in the browser. And when I hit the punctuation mark, the clock should stop. And it did. Awesome. There's only one problem: if I take all the text out, look what happens. The clock starts again. And now, I can't stop it. What's happening here is every time I make a key press, I trigger the start function. The start function says, if the text entered length is absolute equal to zero, which it is when I erase everything in this test area, then start the interval.

The problem is, we are now starting a new interval that is not the same as before. It'll have a new index number, so we can't clear it. That's a problem. But again, we can solve it with some simple logic. If I go back up to the top here, I'll create a new variable called timer running, and I'll set it to false. That means when the script originally loads, the timer is not running. That makes sense, right? Then we go down to the start function, and we say, if text entered length is absolute equal to zero, and not timer running, meaning timer running is set to false, then we set timer running to true and save the script.

So what happens now is the first time we start typing in this box, timer running is set to true, and that means even if we clear the interval, so everything stops once we're done, we still won't run this interval set interval function again because timer running is now true. That means I can now go back in again, text to test, clock stops. I can erase the text. Clock does not start again. Can you see the finish line? It's almost there. Just one more movie.