Making a Sass mixin with optional arguments

Question

I am writing a mixin like this    mixin box-shadow  top   left   blur   color   inset           -webkit-box-shadow   top  left  blur  color  inset      -moz-box-shadow   top  left  blur  color  inset      box-shadow   top  left  blur  color  inset      When called what I really want is that if no  inset value is passed  nothing is output  rather than it compiling to something like this   -webkit-box-shadow  2px 2px 5px  555555     -moz-box-shadow  2px 2px 5px  555555     box-shadow  2px 2px 5px  555555       How do I rewrite the mixin so that if there is no value of  inset passed  nothing is output

User · Answer

Old question  I know  but I think this is still relevant  Arguably  a clearer way of doing this is to use the unquote   function  which SASS has had since version 3 0 0     mixin box-shadow  top   left   blur   color   inset         -webkit-box-shadow   top  left  blur  color unquote  inset     -moz-box-shadow   top  left  blur  color unquote  inset     box-shadow   top  left  blur  color unquote  inset       This is roughly equivalent to Josh s answer  but I think the explicitly named function is less obfuscated than the string interpolation syntax

User · Answer

With sass 3 4 9       declare  mixin button   bgcolor blue        background  bgcolor      and use without value  button will be blue        use  my button       include button        and with value  button will be red    use  my button       include button  red        works with hexa too

User · Answer

Even DRYer way    mixin box-shadow  args          each  pre in -webkit-  -moz-  -ms-  -o-          pre   box-shadow    args           box-shadow      args       And now you can reuse your box-shadow even smarter    myShadow      include box-shadow 2px 2px 5px  555  inset 0 0 0

User · Answer

Sass supports  if statements   See the documentation    You could write your mixin like this    mixin box-shadow  top   left   blur   color   inset          if  inset             -webkit-box-shadow  top  left  blur  color  inset      -moz-box-shadow  top  left  blur  color  inset      box-shadow  top  left  blur  color  inset

User · Answer

A DRY r Way of Doing It  And  generally  a neat trick to remove the quotes    mixin box-shadow  top   left   blur   color   inset         -webkit-box-shadow   top  left  blur  color    inset     -moz-box-shadow      top  left  blur  color    inset     box-shadow           top  left  blur  color    inset       SASS Version 3   you can use unquote      mixin box-shadow  top   left   blur   color   inset         -webkit-box-shadow   top  left  blur  color unquote  inset     -moz-box-shadow      top  left  blur  color unquote  inset     box-shadow           top  left  blur  color unquote  inset        Picked this up over here  pass a list to a mixin as a single argument with SASS

User · Answer

here is the solution i use  with notes below    mixin transition  trans          if length  trans   lt  1        trans  all  15s ease-out        -moz-transition   trans    -ms-transition   trans    -webkit-transition   trans    transition   trans      use-this      include transition      use-this-2      include transition all 1s ease-out  color 2s ease-in        prefer passing property values as native css to stay close to  the tongue  allow passing variable number of arguments define a default value for laziness

User · Answer

You can put the property with null as a default value and if you don t pass the parameter it will not be interpreted    mixin box-shadow  top   left   blur   color   inset null      -webkit-box-shadow   top  left  blur  color  inset    -moz-box-shadow      top  left  blur  color  inset    box-shadow           top  left  blur  color  inset      This means you can write the include statement like this    include box-shadow  top   left   blur   color     Instead of writing it like this    include box-shadow  top   left   blur   color  null     As shown in the answer here

User · Answer

I know its not exactly the answer you were searching for but you could pass  null  as last argument  when  include box-shadow mixin  like this  include box-shadow 12px  14px  2px  green  null   Now  if that argument is only one in that property than that property  and its  default  value  won t get compiled  If there are two or more args on that  line  only ones that you nulled won t get compiled  your case    CSS output is exactly as you wanted it  but you have to write your nulls        include box-shadow 12px  14px  2px  green  null         compiles to        -webkit-box-shadow  12px 14px 2px green      -moz-box-shadow  12px 14px 2px green      box-shadow  12px 14px 2px green

User · Answer

You can always assign null to your optional arguments  Here is a simple fix   mixin box-shadow  top   left   blur   color   inset null      assigning null to inset value makes it optional     -webkit-box-shadow   top  left  blur  color  inset      -moz-box-shadow   top  left  blur  color  inset      box-shadow   top  left  blur  color  inset

User · Answer

A so much better DRY way  is to pass  args    to the  mixin  That way  no matter how many  args you will pass  In the  input call  you can pass all args needed   Like so    mixin box-shadow  args         -webkit-box-shadow   args    -moz-box-shadow   args    box-shadow   args      And now you can reuse your box-shadow in every class you want by passing all needed args    my-box-shadow      include box-shadow 2px 2px 5px  555  inset 0 0 0

User · Answer

Super simple way  Just add a default value of none to  inset - so    mixin box-shadow  top   left   blur   color   inset  none           Now when no  inset is passed nothing will be displayed

User · Answer

I am new to css compilers  hope this helps            mixin positionStyle  params                    temp nth  params 1                if  temp    null              position  temp                               temp nth  params 2                if  temp    null              top  temp                               temp nth  params 3                if  temp    null              right  temp                               temp nth  params 4                if  temp    null              bottom  temp                              temp nth  params 5                if  temp    null              left  temp                      someClass       include positionStyle absolute 30px 5px null null            output   someClass  position absolute   top  30px   right  5px

User · Answer

mixin box-shadow  left  0   top  0   blur  6px   color  hsla 0 0  0  0 25    inset  false         if  inset           -webkit-box-shadow  inset  left  top  blur  color          -moz-box-shadow  inset  left  top  blur  color          box-shadow  inset  left  top  blur  color         else           -webkit-box-shadow   left  top  blur  color          -moz-box-shadow   left  top  blur  color          box-shadow   left  top  blur  color

[sass] Making a Sass mixin with optional arguments

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