simple microbit zip halo / neopixel program to spin a light around when the device is shaken

zipHaloShakeToSpin.ts

let factor2 = 0
let strip: neopixel.Strip = null
let maxNeighbourBrightness = 0
let pxPos = 0
let maxBrightness = 0
let factor = 0
let fPos = 0
let braking = 0
let accel = 0
let speed = 0
input.onGesture(Gesture.Shake, function () {
    speed += 0.5
})
speed = 0
accel = 0.002
braking = 0.002
factor = 0
maxBrightness = 150
maxNeighbourBrightness = maxBrightness * 1
strip = neopixel.create(DigitalPin.P0, 24, NeoPixelMode.RGB)
strip.clear()
strip.show()
basic.forever(function () {
    if (input.buttonIsPressed(Button.A)) {
        speed += accel
    } else {
        speed += 0 - braking
    }
    if (speed < 0) {
        speed = 0
    }
    fPos += speed
    if (fPos >= 23) {
        fPos += 0 - 23
    }
    pxPos = Math.floor(fPos)
    strip.clear()
    strip.setBrightness(100)
    strip.setPixelColor(pxPos, NeoPixelColors.Blue)
    factor2 = fPos - pxPos
    if (pxPos > 0) {
        strip.setBrightness((1 - factor2) * maxNeighbourBrightness)
        strip.setPixelColor(pxPos - 1, NeoPixelColors.Blue)
    }
    if (pxPos < 23) {
        strip.setBrightness(factor2 * maxNeighbourBrightness)
        strip.setPixelColor(pxPos + 1, NeoPixelColors.Blue)
    }
    strip.show()
})