sku 组合算法

// 库存列表
const skuList = [
  {
    skuId: '0',
    skuGroup: ['红色', '大'],
    remainStock: 7,
    price: 2,
    picUrl: 'https://dummyimage.com/100x100/ff00b4/ffffff&text=大'
  },
  {
    skuId: '1',
    skuGroup: ['红色', '小'],
    remainStock: 3,
    price: 4,
    picUrl: 'https://dummyimage.com/100x100/ff00b4/ffffff&text=小'
  },
  {
    skuId: '2',
    skuGroup: ['蓝色', '大'],
    remainStock: 0,
    price: 0.01,
    picUrl: 'https://dummyimage.com/100x100/0084ff/ffffff&text=大'
  },
  {
    skuId: '3',
    skuGroup: ['蓝色', '小'],
    remainStock: 1,
    price: 1,
    picUrl: 'https://dummyimage.com/100x100/0084ff/ffffff&text=小'
  }
];

// 规格列表
const skuNameList = [
  {
    skuName: "颜色",
    skuValues: ["红色", "蓝色"]
  },
  {
    skuName: "尺寸",
    skuValues: ["大", "小"]
  }
];

/**
 * 获取sku信息
 * @param {Array} selected 已选属性数组
 * @return {Object} skuInfo
 */
function getSkuinfo (selected){
  // 用以记录每个按钮状态的，例如 itemState['红色'] = true 表示高亮
  const attrState = {};
  let picUrl = '';
  let minPrice = Number.MAX_VALUE;
  let maxPrice = 0;
  let remainStock = 0;

  // in array not in others 
  const difference = (array, others) => {
    return array.filter((item) => others.indexOf(item) === -1);
  };
  // every in array in others return true or false
  const isSubset = (array, others) => {
    return array.every((item) => others.indexOf(item) > -1);
  };
  
  skuNameList.foreach(spec => {
    //selected 中有 在 spec.skuValues 里的先删除
    var temp = difference(selected, spec.skuValues)
    
    skuValues.foreach(name => { // 遍历规格 
      // 再加上 这一行的一个规格， 其他行已选和本行规格的组合就出来了
      // 如果组合属于 库存中某个skuGroup的子集 说明这个 规格可选
      var combinedTemp = [...temp, name]; 
      attrState[name] = false; // 先设为false
      for(var i = 0; i < skuList.length; i++){
         var skuGroup = skuList[i].skuGroup
         if(isSubset(combinedTemp, skuGroup)&& skuList[i].remainStock) 
         { 
            attrState[name] = true; 
            break;  //  如果其中有一个库存， 这个属性就可以选，然后退出循环 
         }
      }
    })
  })

  // 实际已选属性，过滤空字符串
  const realSelected = selected.filter((item) => item);
  const defaultSelected = selected.map(
    (name, idx) => name || skuNameList[idx].skuValues[0]
  );
  
  skuList.forEach(sku => {
    if(isSubset(selected,sku.skuGroup)){
     remainStock += sku.remainStock;
      minPrice = Math.min(minPrice, sku.price);
      maxPrice = Math.max(maxPrice, sku.price);
     // 取当前图片
      if (isSubset(defaultSelected, sku.skuGroup)) {
        picUrl = sku.picUrl;
      }
    }
  })


  return {
    attrState,
    picUrl,
    minPrice,
    maxPrice,
    remainStock,
  };
}