Workshop › Typing Rain › Step 26 of 33

Accuracy

What we are doing

Every key that did not help (a letter no word starts with, or the wrong next letter) is a mistake. Accuracy is the share of keys that were right.

```js
let letters // correct letters typed
let mistakes

  letters = 0
  mistakes = 0

    if (options.length === 0) {
      mistakes += 1
      return
    }

  if (target.text[typed] !== key) {
    mistakes += 1
    return
  }
  typed += 1
  letters += 1

const accuracy = () => (letters + mistakes === 0 ? 100 : Math.round((100 * letters) / (letters + mistakes)))
```

What it means

• The two one-line returns become blocks that count a mistake first.
• A right letter adds 1 to letters.
• accuracy is 100 * letters / (letters + mistakes), rounded. Before any key it would divide by zero (0 / 0 is NaN in JavaScript), so it returns 100 then.

Your turn

1. Above let best write let letters and let mistakes; at the end of reset, set both to 0.
2. In type, turn the two one-line returns into blocks that add a mistake, and add letters += 1 under typed += 1.
3. Above the keydown listener write accuracy, with an empty line after it.

Skills: Game states, Functions

← Best score Words per minute →

All steps

1. A sky for the words
2. The ground
3. A word on the canvas
4. A function that draws
5. A list of words
6. Make them fall
7. The game loop
8. A new word from the list
9. Let it rain
10. Gone past the ground
11. Lock on to a word
12. Listen to the keyboard
13. Letter by letter
14. Half a word in yellow
15. Let go of a lost word
16. Lives
17. Hearts
18. Score
19. Out of lives
20. Freeze the game
21. The game over panel
22. Play again
23. Levels
24. Faster and faster
25. Best score
26. Accuracy
27. Words per minute
28. Your speed at the end
29. Where the keys go
30. Draw the keyboard
31. Light up the next key
32. Tap the keys
33. Build it yourself: change your mind