JS/TS 對數組中的對象按相同值進行分組

舉個例子：對以下數組按 lastName 的值進行分組分類

const listData = [
  { firstName: "Rick", lastName: "Sanchez", size: 18 },
  { firstName: "Morty", lastName: "Smith", size: 6 },
  { firstName: "Jerry", lastName: "Smith", size: 3 },
  { firstName: "Beth", lastName: "Smith", size: 0 },
  { firstName: "Summer", lastName: "Smith", size: 0 },
  { firstName: "Rick", lastName: "Sanchez", size: 18 },
  { firstName: "Morty", lastName: "Smith", size: 6 },
];

分組前：

分組后：

一、普通寫法

const sortClass = (sortData) => {
  const groupBy = (array, f) => {
    let groups = {};
    array.forEach((o) => {
      let group = JSON.stringify(f(o));
      groups[group] = groups[group] || [];
      groups[group].push(o);
    });
    return Object.keys(groups).map((group) => {
      return groups[group];
    });
  };
  const sorted = groupBy(sortData, (item) => {
    return item.lastName; // 返回需要分組的對象
  });
  return sorted;
};

// 分組前
console.log(listData);
// 分組后
console.log(sortClass(listData));

二、TS 寫法

const sortClass = (sortData: ListDataItem[]) => {
  const groupBy = (array: ListDataItem[], f: Function) => {
    const groups: {
      [key: string]: ListDataItem[],
    } = {};
    array.forEach((item) => {
      const group = JSON.stringify(f(item));
      groups[group] = groups[group] || [];
      groups[group].push(item);
    });
    return Object.keys(groups).map((group) => {
      return groups[group];
    });
  };
  const sorted = groupBy(sortData, (item: ListDataItem) => {
    return item.lastName;
  });
  return sorted;
};

// 分組前
console.log(listData);
// 分組后
console.log(sortClass(listData));