Using css transform property in jQuery

If you want to use a specific transform function, then all you need to do is include that function in the value. For example:

$('.user-text').css('transform', 'scale(' + ui.value + ')');

Secondly, browser support is getting better, but you'll probably still need to use vendor prefixes like so:

$('.user-text').css({
  '-webkit-transform' : 'scale(' + ui.value + ')',
  '-moz-transform'    : 'scale(' + ui.value + ')',
  '-ms-transform'     : 'scale(' + ui.value + ')',
  '-o-transform'      : 'scale(' + ui.value + ')',
  'transform'         : 'scale(' + ui.value + ')'
});

jsFiddle with example: http://jsfiddle.net/jehka/230/