js根据对象数组中某一属性值，合并相同项，并对某一属性累加处理

    test() {
      // js根据对象数组中某一属性值，合并相同项，并对某一属性累加处理
      // Example: 根据code合并数组，并将sl值累加，如下两种方法：
      let data = [
        { code: 1001, name: "苹果", sl: 11 },
        { code: 1001, name: "苹果", sl: 11 },
        { code: 1001, name: "苹果", sl: 11 },
        { code: 1001, name: "苹果", sl: 11 },
        { code: 1002, name: "西瓜", sl: 11 },
        { code: 1002, name: "西瓜", sl: 15 },
        { code: 1003, name: "梨", sl: 15 },
        { code: 1003, name: "梨", sl: 15 }
      ];

      // 第一种：根据对象key的唯一性，累加sl值
      let item = {};
      for (let i = 0; i < data.length; i++) {
        item[data[i].code] = ~~item[data[i].code] + data[i].sl;
      }
      console.log(item);
      // 结果： {1001: 44, 1002: 26, 1003: 30}
      // 第二种：根据reduce遍历累加，得到数组
      let newArray = data.reduce((total, cur, index) => {
        let hasValue = total.findIndex(current => {
          return current.code === cur.code;
        });
        hasValue === -1 && total.push(cur);
        hasValue !== -1 && (total[hasValue].sl = total[hasValue].sl + cur.sl);
        return total;
      }, []);
      console.log(newArray);
      // 结果：
      // [
      //   { code: 1001, name: "苹果", sl: 44 },
      //   { code: 1002, name: "西瓜", sl: 26 },
      //   { code: 1003, name: "梨", sl: 30 }
      // ];
    }