41 lines
1.2 KiB
Markdown
41 lines
1.2 KiB
Markdown
# On Button Pressed
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Register an [event handler](/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](/device/simulator) with this function in a web browser, click an on-screen input button - labelled A or B.
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```sig
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input.onButtonPressed(Button.A, () => {})
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```
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### Example: count button clicks
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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.
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```blocks
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let count = 0
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basic.showNumber(count)
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input.onButtonPressed(Button.A, () => {
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count++;
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basic.showNumber(count);
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})
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```
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### Example: roll a dice
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This example generates a random number when you press the B input button, and then displays a random die image:
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```blocks
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input.onButtonPressed(Button.B, () => {
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let dice = Math.random(6)
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basic.showNumber(dice)
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})
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```
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### Lessons
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[smiley](/lessons/smiley), [answering machine](/lessons/answering-machine), [screen wipe](/lessons/screen-wipe), [rotation animation](/lessons/rotation-animation)
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### See also
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[button is pressed](/reference/input/button-is-pressed), [forever](/reference/basic/forever)
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