自己的第一個點餐小程序，主要包括左右菜單聯動、點擊數量加減、菜單和購物車數量可以同步加減、購物車動畫等，純前端實現

大致的功能樣式如下圖展示：

 

代碼塊

主要代碼塊：

  // 點擊左側分類切換右側菜品
  changeRightMenu: function (e) {
    var classify = e.target.dataset.id;// 獲取點擊項的id
    var foodList = this.data.foodList;
    var allFoodList = this.data.allFoodList;
    var newFoodList = [];
    if (classify == 0) {//選擇了全部選項
      this.setData({
        curNav: classify,
        foodList: allFoodList
      })
    } else { //選擇了其他選項
      for (var i in allFoodList) {
        if (allFoodList[i].catid == classify) {
          newFoodList.push(allFoodList[i])
        }
      }
      this.setData({
        // 右側菜單當前顯示第curNav項
        curNav: classify,
        foodList: newFoodList
      })
    }
  },

 // 購物車及菜單中增加數量
  addCount: function (e) {
    var id = e.currentTarget.dataset.id;[這里寫鏈接內容](http://download.csdn.net/download/m0_37543652/10019843%20%20%E6%BA%90%E7%A0%81%E4%B8%8B%E8%BD%BD%E5%9C%B0%E5%9D%80)
    var arr = wx.getStorageSync('cart') || [];
    var f = false;
    for (var i in this.data.foodList) {// 遍歷菜單找到被點擊的菜品，數量加1
      if (this.data.foodList[i].id == id) {
        this.data.foodList[i].quantity += 1;
        if (arr.length > 0) {
          for (var j in arr) {// 遍歷購物車找到被點擊的菜品，數量加1
            if (arr[j].id == id) {
              arr[j].quantity += 1;
              f = true;
              try {
                wx.setStorageSync('cart', arr)
              } catch (e) {
                console.log(e)
              }
              break;
            }
          }
          if (!f) {
            arr.push(this.data.foodList[i]);
          }
        } else {
          arr.push(this.data.foodList[i]);
        }
        try {
          wx.setStorageSync('cart', arr)
        } catch (e) {
          console.log(e)
        }
        break;
      }
    }

    this.setData({
      cartList: arr,
      foodList: this.data.foodList
    })
    this.getTotalPrice();
  },
  // 定義根據id刪除數組的方法
  removeByValue: function (array, val) {
    for (var i = 0; i < array.length; i++) {
      if (array[i].id == val) {
        array.splice(i, 1);
        break;
      }
    }
  },
  // 購物車減少數量
  minusCount: function (e) {
    var id = e.currentTarget.dataset.id;
    var arr = wx.getStorageSync('cart') || [];
    for (var i in this.data.foodList) {
      if (this.data.foodList[i].id == id) {
        this.data.foodList[i].quantity -= 1;
        if (this.data.foodList[i].quantity <= 0) {
          this.data.foodList[i].quantity = 0;
        }
        if (arr.length > 0) {
          for (var j in arr) {
            if (arr[j].id == id) {
              arr[j].quantity -= 1;
              if (arr[j].quantity <= 0) {
                this.removeByValue(arr, id)
              }
              if (arr.length <= 0) {
                this.setData({
                  foodList: this.data.foodList,
                  cartList: [],
                  totalNum: 0,
                  totalPrice: 0,
                })
                this.cascadeDismiss()
              }
              try {
                wx.setStorageSync('cart', arr)
              } catch (e) {
                console.log(e)
              }
            }
          }
        }
      }
    }
    this.setData({
      cartList: arr,
      foodList: this.data.foodList
    })
    this.getTotalPrice();
  },