While

Repeat code in a loop while a condition is true.

@parent javascript/language

Repeat code while a Boolean condition is true.

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let condition = false

~

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while (condition) {
    // This code runs if `condition` is `true`
}

The while loop has a condition that evaluates to a Boolean value. After the do keyword, add the code that you want to run while the condition is true. The while loop concludes with end while.

The condition is tested before any code runs. Which means that if the condition is false, the code inside the loop doesn't execute. Use the break statement to exit a while loop before it's complete.

Example: diagonal line

The following example uses a while loop to make a diagonal line on the LED screen (points 0, 0, 1, 1, 2, 2, 3, 3, 4, 4).

// index is set to 4

let index = 4
while (index >= 0) {
    led.plot(index, index)
    // // subtract 1 from `index` each time through loop
    index = index - 1
}

Example: count until A button pressed

The following example shows numbers on the screen(0, 1, 2, 3...), until the "A" button is pressed.

let x = 0
while (true) {
    basic.showNumber(x, 100)
    let pressed = input.buttonIsPressed("A")
    if (pressed) {
        break
    } else {
        x = x + 1
    }
    basic.pause(1000)
}

Lessons

rotation animation, digi yoyo

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