Template:Px/doc
This template makes it easy to let values for parameters have the suffix "px" removed, to make sure there's only one suffix. For example when a width of a certain element is to be entered, the template could have <span style="width:{{px|{{{width}}}}}px;">contents</span>
so that for when the template is used, the values |width=50
and |width=50px
will both result in a width of 50 pixels. When plain parameters would be used, entering |width=50px
would result in width:50pxpx;
which wouldn't do anything.