[英]Recursive Function in TypeScript - Parents Array
我想創建一個遞歸 function 接收包含 id 和 parent_id 的對象列表。 如果元素的父元素在列表中,我想將其刪除並將其添加到父元素。
轉換這個:
{
"id": 180,
"children": [],
"parent_id": 195,
"name": "Object 180"
},
{
"id": 193,
"children": [],
"parent_id": 180,
"name": "Object 193"
},
{
"id": 194,
"children": [],
"parent_id": 180,
"name": "Object 194"
}
{
"id": 199,
"children": [],
"parent_id": 187,
"name": "Object 199"
}
{
"id": 304,
"children": [],
"parent_id": 193,
"name": "Object 304"
}
對此:
{
"id": 180,
"children": [
{
"id": 193,
"children": [
{
"id": 304,
"children": [],
"parent_id": 193,
"name": "Object 304"
}
],
"parent_id": 180,
"name": "Object 193"
},
{
"id": 194,
"children": [],
"parent_id": 180,
"name": "Object 194"
}
],
"parent_id": 195,
"name": "Object 180"
},
{
"id": 199,
"children": [],
"parent_id": 187,
"name": "Object 199"
}
有時parent_id是null,並且沒有父母等級限制。
您不需要遞歸 function。 只需跟蹤您已經看過的項目,如果其中存在父項,則添加到parent.children
或添加新的根節點。
附上一個完整的示例解決方案。
type Item = {
id: number,
children: Item[],
parent_id: number,
name: string,
}
const items: Item[] = [
{
"id": 180,
"children": [],
"parent_id": 195,
"name": "Object 180"
},
{
"id": 193,
"children": [],
"parent_id": 180,
"name": "Object 193"
},
{
"id": 194,
"children": [],
"parent_id": 180,
"name": "Object 194"
},
{
"id": 199,
"children": [],
"parent_id": 187,
"name": "Object 199"
},
{
"id": 304,
"children": [],
"parent_id": 193,
"name": "Object 304"
}
];
function nest(items:Item[]): Item[] {
const output: Item[] = [];
const idToItem = new Map<number,Item>();
for (let item of items) {
// Either add to parent. Or create a new root level node
if (idToItem.has(item.parent_id)) {
idToItem.get(item.parent_id)!.children.push(item);
} else {
idToItem.set(item.id, item);
output.push(item);
}
}
return output;
}
console.log(nest(items));
由於 basarat 的答案沒有考慮嵌套超過一層的項目。
這是一個創建具有任意嵌套深度的 output 的解決方案:
const listToTree = (input) => { const map = new Map(input.map((item) => [item.id, item])); const output = []; for (const item of input) { if (map.has(item.parent_id)) { map.get(item.parent_id).children.push(map.get(item.id)); } else { output.push(map.get(item.id)); } } return output; }; const input = [ { "id": 180, "children": [], "parent_id": 195, "name": "Object 180" }, { "id": 193, "children": [], "parent_id": 180, "name": "Object 193" }, { "id": 194, "children": [], "parent_id": 180, "name": "Object 194" }, { "id": 199, "children": [], "parent_id": 187, "name": "Object 199" }, { "id": 304, "children": [], "parent_id": 193, "name": "Object 304" }, { "id": 305, "children": [], "parent_id": 194, "name": "Object 304" } ]; const output = listToTree(input); console.log(output);
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