Question

I’m trying to loop from 1 to 12 and output some span widths for an altered grid for a particular view in an app.

$span-width: 8.21875%;
$gap: 0.125%;
@for $i from 1 through 12 {
  $span-width: ($i * $span-width) + ($i * $gap) ;
  .span#{$i}{
    width: $span-width;     
 }
}

This is outputting

.span6 {
  width: 6162%;
}

How do I write the sass to calculate the widths using the usual arithmetic rules?

Answer 1

The expression you want is this: ($i * ($span-width / 1%)) + ($i * ($gap / 1%)). Alternately, you could drop the % from your $span-width/$gap variables.

Edit: not sure why assigning the variable to the expression isn’t working (I had only tested it using @debug)

$span-width: 8.21875%;
$gap: 0.125%;
@for $i from 1 through 12 {
    @debug (($i * ($span-width / 1%)) + ($i * ($gap / 1%))) * 1%;
    .span#{$i}{
        width: (($i * ($span-width / 1%)) + ($i * ($gap / 1%))) * 1%;
    }
}

Generates this:

.span1{width:8.34375%}
.span2{width:16.6875%}
.span3{width:25.03125%}
.span4{width:33.375%}
.span5{width:41.71875%}
.span6{width:50.0625%}
.span7{width:58.40625%}
.span8{width:66.75%}
.span9{width:75.09375%}
.span10{width:83.4375%}
.span11{width:91.78125%}
.span12{width:100.125%}

If you really need to reuse the variable, you might want to consider making a function for it.