41 lines
1.3 KiB
Markdown
41 lines
1.3 KiB
Markdown
|
# On Button Pressed
|
||
|
|
|
||
|
|
Register an [event handler](/microbit/reference/event-handler) that will execute whenever an input button (A, B, or A and B together) is pressed during program execution. When [running code](/microbit/js/simulator) with this function in a web browser, click an on-screen input button - labelled A or B.
|
||
|
|
|
||
|
|
```sig
|
||
|
|
input.onButtonPressed(Button.A, () => {})
|
||
|
|
```
|
||
|
|
|
||
|
|
### Example: count button clicks
|
||
|
|
|
||
|
|
This example counts how many times the left or right input button is pressed. Each time a button is pressed, the global count variable is increased by 1 and displayed on the screen.
|
||
|
|
|
||
|
|
```blocks
|
||
|
|
let count = 0
|
||
|
|
basic.showNumber(count)
|
||
|
|
input.onButtonPressed(Button.A, () => {
|
||
|
|
count++;
|
||
|
|
basic.showNumber(count);
|
||
|
|
})
|
||
|
|
```
|
||
|
|
|
||
|
|
### Example: roll a dice
|
||
|
|
|
||
|
|
This example generates a random number when you press the B input button, and then displays a random die image:
|
||
|
|
|
||
|
|
```blocks
|
||
|
|
input.onButtonPressed(Button.B, () => {
|
||
|
|
let dice = Math.random(6)
|
||
|
|
basic.showNumber(dice)
|
||
|
|
})
|
||
|
|
```
|
||
|
|
|
||
|
|
### Lessons
|
||
|
|
|
||
|
|
[smiley](/microbit/lessons/smiley), [answering machine](/microbit/lessons/answering-machine), [screen wipe](/microbit/lessons/screen-wipe), [rotation animation](/microbit/lessons/rotation-animation)
|
||
|
|
|
||
|
|
### See also
|
||
|
|
|
||
|
|
[button is pressed](/microbit/reference/input/button-is-pressed), [forever](/microbit/reference/basic/forever)
|
||
|
|
|