{
  "url": "https://unifast.dev/zh-CN/docs/packages/core/visit-hast/",
  "locale": "zh-CN",
  "title": "visitHast()",
  "description": "通过访问者函数遍历并转换 HAST 树。",
  "section": "packages",
  "body": "```ts\nimport { visitHast } from \"@unifast/core\";\n```\n\n## 签名\n\n```ts\nfunction visitHast(node: HastNode, visitor: (node: HastNode) => HastNode | void): HastNode\n```\n\n## 参数\n\n### node\n\n| 属性 | 类型 | 默认值 | 描述 |\n|----------|------|---------|-------------|\n| `type` | `string` | — | 节点类型（`\"root\"`、`\"element\"`、`\"text\"` 等） |\n| `children` | `HastNode[]` | — | 子节点（用于 `\"root\"` 和 `\"element\"` 类型） |\n\n### visitor\n\n| 属性 | 类型 | 默认值 | 描述 |\n|----------|------|---------|-------------|\n| `visitor` | `(node: HastNode) => HastNode \\| void` | — | 对每个节点调用的函数；返回新节点可替换原节点，返回 `void` 则保留原节点 |\n\n## 返回值\n\n`HastNode` —— 应用 visitor 转换后的新树。\n\n## 用法\n\n```ts\nimport { visitHast } from \"@unifast/core\";\nimport type { HastNode, HastRoot } from \"@unifast/core\";\n\nconst tree: HastRoot = {\n  type: \"root\",\n  children: [\n    {\n      type: \"element\",\n      tagName: \"p\",\n      properties: {},\n      children: [{ type: \"text\", value: \"Hello world\" }],\n    },\n  ],\n};\n\nconst result = visitHast(tree, (node) => {\n  if (node.type === \"text\") {\n    return { type: \"text\", value: node.value.toUpperCase() };\n  }\n});\n\nconsole.log(result);\n// Tree with text \"HELLO WORLD\"\n```\n\n## 示例\n\n### 为所有段落添加类名\n\n```ts\nimport { visitHast } from \"@unifast/core\";\nimport type { HastRoot } from \"@unifast/core\";\n\nconst tree: HastRoot = {\n  type: \"root\",\n  children: [\n    {\n      type: \"element\",\n      tagName: \"p\",\n      properties: {},\n      children: [{ type: \"text\", value: \"First paragraph.\" }],\n    },\n    {\n      type: \"element\",\n      tagName: \"p\",\n      properties: {},\n      children: [{ type: \"text\", value: \"Second paragraph.\" }],\n    },\n  ],\n};\n\nconst result = visitHast(tree, (node) => {\n  if (node.type === \"element\" && node.tagName === \"p\") {\n    return {\n      ...node,\n      properties: { ...node.properties, className: [\"prose\"] },\n    };\n  }\n});\n\n// Both <p> elements now have className: [\"prose\"]\n```\n\n### 移除所有图片\n\n```ts\nimport { visitHast } from \"@unifast/core\";\nimport type { HastRoot } from \"@unifast/core\";\n\nconst tree: HastRoot = {\n  type: \"root\",\n  children: [\n    {\n      type: \"element\",\n      tagName: \"p\",\n      properties: {},\n      children: [\n        { type: \"text\", value: \"See the photo: \" },\n        {\n          type: \"element\",\n          tagName: \"img\",\n          properties: { src: \"photo.jpg\", alt: \"A photo\" },\n          children: [],\n        },\n      ],\n    },\n  ],\n};\n\nconst result = visitHast(tree, (node) => {\n  if (node.type === \"element\" && (node.tagName === \"p\" || node.tagName === \"div\")) {\n    return {\n      ...node,\n      children: node.children.filter(\n        (child) => !(child.type === \"element\" && child.tagName === \"img\"),\n      ),\n    };\n  }\n});\n\n// The <img> element has been removed from the tree\n```\n\n### 收集所有链接\n\n```ts\nimport { visitHast } from \"@unifast/core\";\nimport type { HastRoot } from \"@unifast/core\";\n\nconst tree: HastRoot = {\n  type: \"root\",\n  children: [\n    {\n      type: \"element\",\n      tagName: \"p\",\n      properties: {},\n      children: [\n        { type: \"text\", value: \"Visit \" },\n        {\n          type: \"element\",\n          tagName: \"a\",\n          properties: { href: \"https://example.com\" },\n          children: [{ type: \"text\", value: \"Example\" }],\n        },\n        { type: \"text\", value: \" and \" },\n        {\n          type: \"element\",\n          tagName: \"a\",\n          properties: { href: \"https://docs.example.com\" },\n          children: [{ type: \"text\", value: \"Docs\" }],\n        },\n      ],\n    },\n  ],\n};\n\nconst links: string[] = [];\n\nvisitHast(tree, (node) => {\n  if (node.type === \"element\" && node.tagName === \"a\") {\n    const href = node.properties.href;\n    if (typeof href === \"string\") {\n      links.push(href);\n    }\n  }\n});\n\nconsole.log(links);\n// [\"https://example.com\", \"https://docs.example.com\"]\n```\n\n### 将代码块包裹在容器中\n\n```ts\nimport { visitHast } from \"@unifast/core\";\nimport type { HastNode, HastRoot } from \"@unifast/core\";\n\nconst tree: HastRoot = {\n  type: \"root\",\n  children: [\n    {\n      type: \"element\",\n      tagName: \"pre\",\n      properties: {},\n      children: [\n        {\n          type: \"element\",\n          tagName: \"code\",\n          properties: { className: [\"language-js\"] },\n          children: [{ type: \"text\", value: \"const x = 1;\" }],\n        },\n      ],\n    },\n  ],\n};\n\nconst result = visitHast(tree, (node) => {\n  if (node.type === \"element\" && node.tagName === \"pre\") {\n    return {\n      type: \"element\",\n      tagName: \"div\",\n      properties: { className: [\"code-block\"] },\n      children: [node],\n    } as HastNode;\n  }\n});\n\n// <pre> is now wrapped inside <div class=\"code-block\">\n```\n\n## 行为说明\n\n- **不可变：** 返回一棵新树，原树不会被修改\n- **自顶向下遍历：** visitor 先对父节点调用，然后再访问其子节点\n- **替换：** 如果 visitor 返回一个节点，该节点会在子节点被遍历之前替换掉当前节点\n- **空操作：** 如果 visitor 返回 `void`（或 `undefined`），则保留原节点\n- **递归：** `\"root\"` 和 `\"element\"` 节点的子节点会被递归访问",
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