code: function (_, escaped) {
              var high = '0x' + escaped - 65536;    // NaN means non-codepoint
              // NaN means non-codepoint
              return isNaN(high) ? escaped : // BMP codepoint
              high < 0 ? String.fromCharCode(high + 65536) : // Supplemental Plane codepoint (surrogate pair)
              String.fromCharCode(high >> 10 | 55296, high & 1023 | 56320);
          }
docs: CSS escapes http://www.w3.org/TR/CSS21/syndata.html#escaped-characters CSS escapes http://www.w3.org/TR/CSS21/syndata.html#escaped-characters