Type check in SCSS?

Basically I am attempting to set a CSS value based on whether a value passed into an SCSS mixin is even or odd.

Done some looking around and have found diddly squat. Any mention of odd / even in a search term with CSS/SCSS just results in :nth-child results.

Remainder operator doesn’t work in CSS so that method of determining an odd / even number wont work. I then attempted to go down the route where a number divided by 2 would result in either a number type or integer type depending if it was even or odd, nope.

My only feasible option seems to be

$valType1: "odd";

   @if $val1 == 2 {
    $valType1: "even";
  } @else if $val1 == 4 {
    $valType1: "even";
  } @else if $val1 == 6 {
    $valType1: "even";
  } @else if $val1 == 8 {
    $valType1: "even";
  } @else if $val1 == 10 {
    $valType1: "even";
  } @else if $val1 == 12 {
    $valType1: "even";
  } @else if $val1 == 14 {
    $valType1: "even";
  } @else if $val1 == 16 {
    $valType1: "even";
  } @else if $val1 == 18 {
    $valType1: "even";
  } @else if $val1 == 20 {
    $valType1: "even";
  } @else if $val1 == 22 {
    $valType1: "even";
  } @else if $val1 == 24 {
    $valType1: "even";
  } @else if $val1 == 26 {
    $valType1: "even";
  }

  @if $valType1 == "even" {
    background-color: red;
  }
  

There’s gotta be something. Any help suggestions? Am I overlooking something painfully obvious?

Thank you!

>Solution :

This is a good use of @function instead of a mixin. And you can use the % modulo operator for this.

Added a @mixin for clarity (and another option).

@function evenOdd( $value) {
    $number : blue;
    
    @if ($value % 2 == 0) {
        $number : red 
    }
    
    @return $number;
}

@mixin evenOdd( $value ) {
    @if ($value % 2 == 0) {
        background-color: red;
    } @else {
        background-color: blue;
    }
}

.selector {
    background-color: evenOdd(2);
    /* compiles to red */
}

.selector {
    background-color: evenOdd(3);
    /* compiles to blue */
}

.selector {
    background-color: evenOdd(4);
    /* compiles to red */
}

/* MIXINS */
.selector {
    @include evenOdd(2);
    /* compiles to background-color: red */
}

.selector {
    @include evenOdd(3);
    /* compiles to background-color: blue */
}

You can past this into https://www.sassmeister.com/ – and watch the magic happen.