pxt-calliope/docs/reference/js/lessons/break/challenges.md

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2016-03-26 00:47:20 +01:00
# break challenges
This guide will show you how to use a break statement within a while loop. #docs
### Challenge 0
Welcome! This [guided tutorial](/microbit/lessons/break/tutorial) will assist you with this activity.
```
count = 0
shouldBreak = false
input.onButtonPressed("A", () => {
shouldBreak = true
})
while (true) {
if (shouldBreak) {
basic.showString("I'M OUT!", 150)
images.createImage(`
# . . . #
# . . . #
. . # . .
# . . . #
. # # # .
`).showImage(0)
break
}
count = count + 1
basic.showNumber(count, 150)
basic.pause(1000)
}
```
### Challenge 1
Try to remove the `break` in the `if` loop. What problem does this create?
### Challenge 2
Now let's resume the timer again once button `B` is pressed! To do so, begin by creating a condition to know when button `B` is pressed.
```
// **. . .**
while (true) {
if (shouldBreak) {
basic.showString("I'M OUT!", 150)
break
}
count = count + 1
basic.showNumber(count, 150)
basic.pause(1000)
}
input.onButtonPressed("B", () => {
}) // ***
```
Next, set `shouldBreak` back to false to indicate we want to run the `while` loop again.
```
// **. . .**
input.onButtonPressed("B", () => {
shouldBreak = false // ***
})
```
And now copy the code from the previous while loop into the condition of `input->on button pressed("B")`. This will resume the counter.
```
// **. . .**
input.onButtonPressed("B", () => {
shouldBreak = false
while (true) {
if (shouldBreak) {
basic.showString("I'M OUT!", 150) // ***
break // ***
}
count = count + 1 // ***
basic.showNumber(count, 150) // ***
basic.pause(1000) // ***
}
})
```
### Challenge 3
Notice that the two `while` loops are identical. Clean up this redundancy in your code by creating another method and then placing the `while` loop in the method.