Workshop › Conway's Game of Life › Step 19 of 32

One place for the buttons

What we are doing

Soon there will be keys and on-screen buttons doing the same things. So every action goes through one function, press(button): 'Play' starts or stops the world, 'Step' stops it and advances one generation.

```js
function press(button) {
  if (button === 'Play') playing = !playing
  else if (button === 'Step') {
    playing = false
    step()
  }
}
```

What it means

• button is the name of the button pressed.
• !playing is the opposite of playing, so 'Play' flips it on and off.
• else if checks the next case only when the first one was not true.

Your turn

Write press above the keydown listener, with an empty line between them.

Skills: Functions, Game states

← Running or not Space to play, N to step →

All steps

1. The board
2. Measure the grid
3. One living cell
4. A function that draws
5. The world in memory
6. Draw every living cell
7. A random soup
8. Count the neighbours
9. Four rules
10. Draw again and again
11. Next generation with N
12. Count the generations
13. Show the generation
14. A world without edges
15. Count the living
16. A generation every few frames
17. Let it live
18. Running or not
19. One place for the buttons
20. Space to play, N to step
21. Clear and shuffle
22. Where is the pointer?
23. Which cell?
24. Click a cell
25. Paint or erase?
26. Drag to paint
27. Patterns from text
28. The glider gun
29. Fire the gun
30. Buttons on the screen
31. Tap the buttons
32. Build it yourself: a world at rest