FastLED strobing effect

bool isOn = false;
uint32_t lastStrobeMs = 0; // The previous light change time.
uint8_t strobeMs = 50; // Strobing frequency
CRGB strobeColor = CRGB::White;

void setup() {
  // The usual FastLED setup stuff
}

void loop() {
  // Read from sensors etc. to change strobeMs and/or strobeColor values here.

  uint32_t ms = millis();
  if (ms - lastStrobeMs >= strobeMs) {
    fill_solid(leds, NUM_LEDS, isOn ? CRGB::Black : strobeColor);
    isOn = !isOn;
    lastStrobeMs = ms;
  }
}