pxt-calliope/docs/reference/basic/forever.md

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# Forever
Keep running part of a program
[in the background](/reference/control/in-background).
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```sig
basic.forever(() => {
})
```
### Example: compass
The following example constantly checks the
[compass heading](/reference/input/compass-heading)
and updates the screen with the direction.
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```blocks
basic.forever(() => {
let heading = input.compassHeading()
if (heading < 45) {
basic.showString("N", 100)
} else if (heading < 135) {
basic.showString("E", 100)
}
else if (heading < 225) {
basic.showString("S", 100)
}
else {
basic.showString("W", 100)
}
})
```
### Example: counter
The following example keeps showing the [number](/reference/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 BBC micro:bit.
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```blocks
let num = 0
basic.forever(() => {
basic.showNumber(num, 150)
})
input.onButtonPressed(Button.A, () => {
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num = num + 1
})
```
### Competing for the LED screen
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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 micro:bit:
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```blocks
basic.forever(() => {
basic.showNumber(6789, 150)
})
input.onButtonPressed(Button.A, () => {
basic.showNumber(2, 150)
})
```
### Lessons
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[blink](/lessons/blink), [snowflake-fall](/lessons/snowflake-fall), [flashing-heart](/lessons/flashing-heart)
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### See also
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[while](/reference/loops/while), [on button pressed](/reference/input/on-button-pressed), [in background](/reference/control/in-background)
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