pxt-calliope/docs/reference/basic/forever.md
Juri Wolf a93febb5b7
Map and clean deprecated functions (#175)
* add image and deprecated arrow functions

* update locales

* map basic.showArrow

* map arrow blocks

* map & remove arrow images

* remove arrow blocks

* update locales

* remove & patch:
rgbw -> rgb
button/pin pressed -> button/pin event
loudness -> soundLevel

* update ts mappings for arrows

* add wip ts patch rules

* update .blocks files

* use Click instead of Down as default in Documentation and tests

* patch test.blocks

* fix lowercase name tag

* update test.blocks

* update blocks test files

* update blocks test files

* format block files

* pass blocks file tests

* fix ts mapping

* fix color.defl value

closes https://github.com/microsoft/pxt-calliope/issues/136

* fix ts mappings

- add optional spacing at the end of rgbw()
- map up to v4.0.19

* add suggested changes

* replace innerText by textContent

Co-authored-by: JW <gitkraken@juriwolf.de>
Co-authored-by: Juri <info@juriwolf.de>
2022-04-26 10:28:42 -07:00

71 lines
1.5 KiB
Markdown

# Forever
Keep running part of a program
[in the background](/reference/control/in-background).
```sig
basic.forever(() => {
})
```
## Example: compass
The following example constantly checks the
[compass heading](/reference/input/compass-heading)
and updates the screen with the direction.
```blocks
let degrees = 0
basic.forever(() => {
degrees = input.compassHeading()
if (degrees < 45) {
basic.showString("N")
} else if (degrees < 135) {
basic.showString("E")
} else if (degrees < 225) {
basic.showString("S")
} else if (degrees < 315) {
basic.showString("W")
} else {
basic.showString("N")
}
})
```
## Example: counter
The following example keeps showing the [number](/types/number) stored in a global variable.
When you press button `A`, the number gets bigger.
You can use a program like this to count things with your @boardname@.
```blocks
let num = 0
basic.forever(() => {
basic.showNumber(num)
})
input.onButtonEvent(Button.A, ButtonEvent.Click, () => {
num = num + 1
})
```
## Competing for the LED screen
If different parts of a program are each trying
to show something on the LED screen at the same time,
you may get unexpected results.
Try this on your @boardname@:
```blocks
basic.forever(() => {
basic.showNumber(6789)
})
input.onButtonEvent(Button.A, ButtonEvent.Click, () => {
basic.showNumber(2)
})
```
## See also
[while](/blocks/loops/while), [on button pressed](/reference/input/on-button-pressed), [in background](/reference/control/in-background)