Get jQuery to measure with em instead of px

Question

I have a website that is heavily based on jQuery; meaning much of it's content is created, measured, & set by jQuery.

All these measurements are px. I need to either convert them to em or, preferably, create a function that will convert them for me. This would be easy if all the font-size was 16px (or 100%); this is not the case, however. I need it to detect the font-size of the container & go from there.

Answer 1

I figured it out. You can see the code here.

          function px_to_em(px_value, container) {
          ////////////////////////////////
          // Detect Contianer Font Size //
          ////////////////////////////////

          //Prepend a span tag to the container for testing
          $(container).prepend("<span id='wraping_span_to_test'></span>");

          //Set the span to height 1em and then save the pixel height to the container_ft_sz variable
          container_ft_size = $("#wraping_span_to_test").css({
              "font-family": "inherit",
                  "font-size": "inherit",
                  "font-style": "inherit",
                  "font-variant": "inherit",
                  "font-weight": "inherit",
                  "line-height": "inherit",
                  "margin": "0 !important",
                  "padding": "0 !important",
                  "border": "0 !important",
                  "outline": "0 !important",
                  "background-color": "aqua",
                  "height": "1em",
                  "width": " 1em",
                  "display": "block"
          }).height();

          //Remove the testing span
          $("#wraping_span_to_test").remove();

          //Use values to convert to ems
          var round_to = 1000;
          return Math.round((px_value / container_ft_size) * round_to) / round_to;
      }

This should allow you to find measurements with jQuery that is measured by pixels & convert them into em measurements by calling a simple function.

Answer 2

This isn't easy. Thinking about it you could temporarily insert content with width:1em, measure the width in px, and calculate the em you need from there.