classic.js

 getClassic(nextOrPrev, index){
      const classic = this._getHasClassic(nextOrPrev,index)
      if (!classic) {
        return this.request({
          url: '/classic/' + index + '/' + nextOrPrev
        })
      }
      else{
        return classic
      }      
    }
    
  _getHasClassic(nextOrPrev,index){
      const key = nextOrPrev == 'next' ? this._getKey(index + 1) : this._getKey(index - 1)
      const classic = wx.getStorageSync(key)
      return classic
    }

index.js

    _upClassic(nextOrPrve) {
      const getClassic = classicModel.getClassic(nextOrPrve, this.data.classic.index)
      const hasClassic = classicModel._getHasClassic(nextOrPrve, this.data.classic.index)
      if (hasClassic){
        //console.log(getClassic)
        this._setData(getClassic)
      }
      else{
        getClassic.then(res=>{
          //console.log(res)
          wx.setStorageSync(classicModel._getKey(res.index), res)
          this._getClassicLikeStatus(res.id, res.type)
          this._setData(res)
        })
      }
    },

    _setData(data){
      this.setData({
        classic: data,
        last: classicModel._isLast(data.index),
        frist: classicModel._isFrist(data.index)
      })
    },

已解决，正确的我贴下，仅供参考