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Rewrite in simple English, debug the examples.

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Ron Hale-Evans 2016-05-20 15:33:15 -07:00
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docs/reference/input/on-button-pressed.md
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@ -1,6 +1,9 @@
# On Button Pressed # On Button Pressed
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. Start an [event handler](/reference/event-handler) (part of the program that will run when something happens, like when a button is pressed).
This handler works when button `A` or `B` is pressed, or `A` and `B` together.
When you are using this function in a web browser, click the buttons on the screen instead of the ones
on the BBC micro:bit.
```sig ```sig
input.onButtonPressed(Button.A, () => {}) input.onButtonPressed(Button.A, () => {})
@ -8,7 +11,8 @@ input.onButtonPressed(Button.A, () => {})
### Example: count button clicks ### 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. This example counts how many times you press the `A` button.
Each time you press the button, the [LED screen](/device/screen) shows the `count` variable getting bigger.
```blocks ```blocks
let count = 0 let count = 0
@ -19,22 +23,29 @@ input.onButtonPressed(Button.A, () => {
}) })
``` ```
### Example: roll a dice ### Example: roll dice
This example generates a random number when you press the B input button, and then displays a random die image: This example generates a number from 1 to 6 when you press the `B` button. Then it shows the number.
```blocks ```blocks
input.onButtonPressed(Button.B, () => { input.onButtonPressed(Button.B, () => {
let dice = Math.random(6) let dice = Math.random(6) + 1
basic.showNumber(dice) basic.showNumber(dice)
}) })
``` ```
### ~hint
This program adds a `1` to `random(6)` so the numbers on the dice will come out right.
Otherwise, sometimes they would show a `0`.
### ~
### Lessons ### Lessons
[smiley](/lessons/smiley), [answering machine](/lessons/answering-machine), [screen wipe](/lessons/screen-wipe), [rotation animation](/lessons/rotation-animation) [smiley](/lessons/smiley), [answering machine](/lessons/answering-machine), [screen wipe](/lessons/screen-wipe), [rotation animation](/lessons/rotation-animation)
### See also ### See also
[button is pressed](/reference/input/button-is-pressed), [forever](/reference/basic/forever) [button is pressed](/reference/input/button-is-pressed), [forever](/reference/basic/forever), [random](/reference/math/math)