Sass-unitless()函数

>> unitless(100)
true
>> unitless(100px)
false
>> unitless(100em)
false
>> unitless(100%)
false
>> unitless(1 /2 )
true
>> unitless(1 /2 + 2 )
true
>> unitless(1px /2 + 2 )
false

// 判断如果没有单位则加上单位"px"
@mixin adjust-location($x, $y) {
  @if unitless($x) {    
    $x: 1px * $x;
  }
  @if unitless($y) {    
    $y: 1px * $y;
  }
  position: relative; 
  left: $x; 
  top: $y;
}

.botton{
    @include adjust-location(20px, 30);
}