重新排序对象-将(剪切)对象复制到另一个

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"
  },
];

业务：

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);根本不起作用。

console.log(parents);工作得很好。但我不明白为什么..。let parents_children是如何影响let parents的？有什么更好的解决方案来存档吗？

Answer 1

分配和返回必须是不同的

let parents_children = parents.map(item => {
   item.children = data.
           filter(stop => stop.parent == item.ID);
   return item;
});

//性能更好的

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

我想你忘了从.map()回来了。

尝试以下几点：

let parents_children = parents.map(item => {
   item.children = data.filter(stop => stop.parent == item.ID)
   return item;
});

我希望这能帮到你!