docs: function(num){
          // 非法值默认处理为none
          if(config.rounding !== 'none' && !Math[config.rounding]){
              config.rounding = 'none'
          }
  
          return config.rounding === 'none' ?         
              parseInt((num*config.constant *100)/100) :
              (Math[config.rounding](num*config.constant *100)/100).toString().indexOf('.0') > -1 ? 
                  // 如果结果后边有小数'.0'，直接取整，否则调用Math方法
                  parseInt(Math[config.rounding](num*config.constant *100)/100):
                  Math[config.rounding](num*config.constant *100)/100;
      }