docs: update treeSub

Author: axolo

docs/treeSub.md

@@ -1,13 +1,119 @@
-# treeSub
-
-get sub tree by id, like `{ id, parentId, children: [] }`
-
-## 调用
+# 剪取子树
 
 ```js
 treeSub(tree, id, [options])
 ```
 
+根据主键从树中剪取一棵子树， 如：`{ id, parentId, children: [] }`。
+
+## 参数
+
+|   参数    |   类型   | 默认 |                    说明                     |
+| --------- | -------- | ---- | ------------------------------------------- |
+| `tree`    | `tree`   |      | [树状结构数据](./param.md#tree)             |
+| `id`      | `any`    |      | [主键](./param.md#id)的值，如：`chartIndex` |
+| `options` | `object` |      | [配置选项](./param.md#options)              |
+
 ## 返回
 
-tree
+| 参数 |   类型   |                说明                |
+| ---- | -------- | ---------------------------------- |
+| *    | `object` | 剪取下的子树，注意其类型为**对象** |
+
+## 示例
+
+::: code-group
+```js [调用]
+import { treeSub } from '@axolo/tree-array'
+
+const tree = [{
+  id: 'home',
+  path: '/home',
+  parentId: null
+}, {
+  id: 'chart',
+  path: '/chart',
+  parentId: null,
+  children: [{
+    id: 'chartIndex',
+    path: '/chart/index',
+    parentId: 'chart',
+    children: [{
+      id: 'chartIndexTop',
+      path: '/chart/index/top',
+      parentId: 'chartIndex'
+    }, {
+      id: 'chartIndexActive',
+      path: '/chart/index/active',
+      parentId: 'chartIndex',
+      children: [{
+        id: 'chartIndexActiveMy',
+        path: '/chart/index/active/my',
+        parentId: 'chartIndexActive'
+      }]
+    }]
+  }, {
+    id: 'chartReview',
+    path: '/chart/review',
+    parentId: 'chart'
+  }, {
+    id: 'chartProject',
+    path: '/chart/project',
+    parentId: 'chart',
+    children: [{
+      id: 'chartProjectYou',
+      path: '/chart/project/you',
+      parentId: 'chartProject',
+      test: true
+    }, {
+      id: 'chartProjectMy',
+      path: '/chart/project/my',
+      parentId: 'chartProject',
+      children: [{
+        id: 'chartProjectMyOne',
+        path: '/chart/project/my/one',
+        parentId: 'chartProjectMy'
+      }, {
+        id: 'chartProjectMyTwo',
+        path: '/chart/project/my/two',
+        parentId: 'chartProjectMy'
+      }]
+    }]
+  }]
+}, {
+  id: 'smile',
+  path: '/smile',
+  parentId: null,
+  children: [{
+    id: 'smileIndex',
+    path: '/smile/index',
+    parentId: 'smile',
+    test: true
+  }]
+}]
+
+treeSub(tree, 'chartIndex') // object of sub tree
+```
+
+```json [结果]
+{
+  "id": "chartIndex",
+  "path": "/chart/index",
+  "parentId": "chart",
+  "children": [{
+    "id": "chartIndexTop",
+    "path": "/chart/index/top",
+    "parentId": "chartIndex"
+  }, {
+    "id": "chartIndexActive",
+    "path": "/chart/index/active",
+    "parentId": "chartIndex",
+    "children": [{
+      "id": "chartIndexActiveMy",
+      "path": "/chart/index/active/my",
+      "parentId": "chartIndexActive"
+    }]
+  }]
+}
+```
+:::