重新排序对象 - 将对象复制（剪切）到另一个对象中

Question

数据const data = [  {    "ID": 1,    "parent": "0",    "title": "Test-1"  },  {    "ID": 2,    "parent": "1",    "title": "Test-1-1"  },  {    "ID": 3,    "parent": "0",    "title": "Test-2"  },  {    "ID": 4,    "parent": "0",    "title": "Test-3"  },  {    "ID": 5,    "parent": "4",    "title": "Test-3-1"  },  {    "ID": 6,    "parent": "4",    "title": "Test-3-2"  },];操作：let parents = data.filter(item => item.parent == "0");let parents_children = parents.map(item => item.children = data.filter(stop => stop.parent == item.ID));console.log(parents_children);根本不工作。console.log(parents);工作正常。但我不明白为什么......let parents_children影响如何let parents？对于我要归档的内容，是否有更好的解决方案？

Answer 1

分配和返回必须不同

let parents_children = parents.map(item => {

   item.children = data.

           filter(stop => stop.parent == item.ID);

   return item;

});

// 更好的性能

let result = data2.reduce((map, cur) => {

  if (cur.parent === "0") {

    // parent

    map[cur.ID] = map[cur.ID] || { children: [] };

    map[cur.ID] = { ...map[cur.ID], ...cur };

  } else {

    if (!map[cur.parent]) map[cur.parent] = { children: [] };

    map[cur.parent].children.push(cur);

  }

  return map;

}, {});

let finalResult = [];

for (const key in result) {

  finalResult.push(result[key]);

}

console.log(JSON.stringify(finalResult, null, 4));

工作样本：

const data = [

  { ID: 1, parent: "0", title: "Test-1" },

  { ID: 2, parent: "1", title: "Test-1-1" },

  { ID: 3, parent: "0", title: "Test-2" },

  { ID: 4, parent: "0", title: "Test-3" },

  { ID: 5, parent: "4", title: "Test-3-1" },

  { ID: 6, parent: "4", title: "Test-3-2" }

];

let parents = data.filter(item => item.parent == "0");

let parents_children = parents.map(item => {

  // create new object

  return {

    ...item,

    children : data.filter(stop => stop.parent == item.ID)

  };

});

console.log(JSON.stringify(parents_children, null, 4));

console.log(data);

const data2 = [

  { ID: 1, parent: "0", title: "Test-1" },

  { ID: 2, parent: "1", title: "Test-1-1" },

  { ID: 3, parent: "0", title: "Test-2" },

  { ID: 4, parent: "0", title: "Test-3" },

  { ID: 5, parent: "4", title: "Test-3-1" },

  { ID: 6, parent: "4", title: "Test-3-2" }

];

// Better performance

let result = data2.reduce((map, cur) => {

  if (cur.parent === "0") {

    // parent

    map[cur.ID] = map[cur.ID] || { children: [] };

    map[cur.ID] = { ...map[cur.ID], ...cur };

  } else {

    if (!map[cur.parent]) map[cur.parent] = { children: [] };

    map[cur.parent].children.push(cur);

  }

  return map;

}, {});

let finalResult = [];

for (const key in result) {

  finalResult.push(result[key]);

}

console.log(JSON.stringify(finalResult, null, 4));

.as-console-row {color: blue!important}

Answer 2

.map()你忘了从我相信回来。

尝试以下操作：

let parents_children = parents.map(item => {

   item.children = data.filter(stop => stop.parent == item.ID)

   return item;

});

我希望这有帮助！