code: function _convertToNumber(str) {
          if (typeof str !== "string") {
              return { isNumber: false, value: null };
          }
  
          var val = parseFloat(+str, 10),
              isNum = (typeof val === "number") && !isNaN(val) &&
                      (val !== Infinity) && (val !== -Infinity);
  
          return {
              isNumber: isNum,
              value:    val
          };
      }
docs: If string is a number, then convert it.
  
  @param {string} str  value parsed from page.
  @return { isNumber: boolean, value: ?number }