code: function (fontSpans) {
          var detected = false
          for (var i = 0; i < baseFonts.length; i++) {
            detected = (fontSpans[i].offsetWidth !== defaultWidth[baseFonts[i]] || fontSpans[i].offsetHeight !== defaultHeight[baseFonts[i]])
            if (detected) {
              return detected
            }
          }
          return detected
        }
docs: checks if a font is available