Get in SCSS Mixin inside @each vars from next array entrie

Question

I want to higher my quality standards of frontends and build today a little helper for the background image part:

.html

<div></div>

.scss

@mixin backgroundImage($path: '/assets/images', $fileName: null, $supports: null, $fileType: '.jpg', $unitType: 'px', $startFrom: 0) {
    @each $res in $supports {
        @media only screen and (min-width: $startFrom / 720 / 1280 / 1920 / 2560 / Last not need) and (max-width: $res#{$unitType}) {
            background-image: url("#{$path}#{$fileName}-#{$res}#{$fileType}");
        }
    }
}

div {
    height: 100vh;
    background-size: cover;
    background-repeat: no-repeat;
    background-position: 50%, 50%;
    background-color: navajowhite;
    @include backgroundImage($fileName: 'background', $supports: (720, 1280, 1920, 2560, 3840), $startFrom: 480);
}

I tryed to create a stackblitz, but realized then, that i cant upload there images. So if you need a demo to test, please create in root where the index.html will be a folder named assets/images/ and place there 5 files named background-720, background-1280 etc...

Ok the point is that i need here: (min-width: $startFrom / 720 / 1280 / 1920 / 2560 / Last not need) to get in every @each the number of $supports of the last @each. Just in the first @each i need to use the $startFrom

I know its confusing. But I never wrote complex SCSS Mixins before. I hope someone can help me with that.

Answer 1

Okay i got it now... The final working code:

@mixin resBgImg($path: '/assets/images/', $fileName: null, $resolutions: null, $fileType: '.jpg', $unitType: 'px', $startFrom: 0)
    @for $i from 1 through length($resolutions)
        $min: $startFrom
        @if $i > 1
            $min: nth($resolutions, $i - 1)
        $max: nth($resolutions, $i)
        @if $i == length($resolutions)
            @media only screen and (min-width: $min + 1+$unitType)
                background-image: url("#{$path}#{$fileName}-#{$max}#{$fileType}")
        @else
            @media only screen and (min-width: $min + if($i > 1, 1, 0)+$unitType) and (max-width: $max+$unitType)
                background-image: url("#{$path}#{$fileName}-#{$max}#{$fileType}")