Want to get rid of delay() function, FastLED, PLEASE HELP

Projects Programming
4

What? I use them in most of my FastLED projects.
For example:

// Function to light up all LEDs as gray, but with every 
// tenth LED green and every hundredth is yellow.
void lightEmUp() {
  fill_solid(leds, NUM_LEDS, CRGB::DimGrey);
  for (int i = 0; i < NUM_LEDS; i++) {
    int j = i % 10;                     //j==0 every ten steps
    if (j == 0)  leds[i] = CRGB::Green;
    j = i % 100;                        //j==0 every hundred steps
    if (j == 0)  leds[i] = CRGB::Yellow;
  }
  FastLED.show();
}