SASS cubic bezier function for precalculated CSS easing

cubic-bezier.scss

@function pow($number, $exponent) {
  $value: 1;

  @if $exponent > 0 {
    @for $i from 1 through $exponent {
      $value: $value * $number;
    }
  }

  @return $value;
}

@function cubic-bezier($x, $a, $b, $c, $d) {
  @return 
    ($a * pow(1 - $x, 3)) +
    ($b * 3 * pow(1 - $x, 2) * $x) +
    ($c * 3 * (1 - $x) * pow($x, 2)) +
    ($d * pow($x, 3));
}