linear-gradient的mixin

转载至https://www.sitepoint.com/building-linear-gradient-mixin-sass/

@function legacy-direction($value) {    @if is-direction($value) == false {        @error "Cannot convert '#{$value}' to legacy syntax because it doesn't seem to be a direction.";    }    $conversion-map: (        to top          : bottom,        to top right    : bottom left,        to right top    : left bottom,        to right        : left,        to bottom right : top left,        to right bottom : left top,        to bottom       : top,        to bottom left  : top right,        to left bottom  : right top,        to left         : right,        to left top     : right bottom,        to top left     : bottom right    );    @if map-has-key($conversion-map, $value) {        @return map-get($conversion-map, $value);    }    @return 90deg - $value;}@mixin linear-gradient($direction, $color-stops...) {    @if is-direction($direction) == false {        $color-stops: $direction, $color-stops;        $direction: 180deg;    }    background: nth(nth($color-stops, 1), 1);    background: -webkit-linear-gradient(legacy-direction($direction), $color-stops);    background: linear-gradient($direction, $color-stops);}@function is-direction($value) {    $is-keyword: index((to top, to top right, to right top, to right, to bottom right, to right bottom, to bottom, to bottom left, to left bottom, to left, to left top, to top left), $value);    $is-angle: type-of($value) == 'number' and index('deg' 'grad' 'turn' 'rad', unit($value));    @return $is-keyword or $is-angle;}

使用：

.selector-1 {  @include linear-gradient(#31B7D7, #EDAC7D);}.selector-2 {  @include linear-gradient(to right, #E47D7D 0%, #C195D3 50%, #4FB4E8 100%);}.selector-3 {  @include linear-gradient(42deg, #B58234 0%, #D2B545 50%, #D7C04D 50.01%, #FFFFFF 100%);}

得到css