{
  "url": "https://unifast.dev/ru/docs/packages/core/visit-hast/",
  "locale": "ru",
  "title": "visitHast()",
  "description": "Обходит и преобразует HAST-дерево с помощью функции-посетителя.",
  "section": "packages",
  "body": "```ts\nimport { visitHast } from \"@unifast/core\";\n```\n\n## Сигнатура\n\n```ts\nfunction visitHast(node: HastNode, visitor: (node: HastNode) => HastNode | void): HastNode\n```\n\n## Параметры\n\n### node\n\n| Свойство | Тип | По умолчанию | Описание |\n|----------|------|---------|-------------|\n| `type` | `string` | — | Тип узла (`\"root\"`, `\"element\"`, `\"text\"` и т. д.) |\n| `children` | `HastNode[]` | — | Дочерние узлы (для типов `\"root\"` и `\"element\"`) |\n\n### visitor\n\n| Свойство | Тип | По умолчанию | Описание |\n|----------|------|---------|-------------|\n| `visitor` | `(node: HastNode) => HastNode \\| void` | — | Функция, вызываемая для каждого узла; вернёт узел — исходный будет заменён, вернёт `void` — останется без изменений |\n\n## Возвращаемое значение\n\n`HastNode` — новое дерево с преобразованиями, применёнными функцией-посетителем.\n\n## Использование\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// Дерево с текстом \"HELLO WORLD\"\n```\n\n## Примеры\n\n### Добавление класса ко всем абзацам\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// Оба элемента <p> теперь имеют className: [\"prose\"]\n```\n\n### Удаление всех изображений\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// Элемент <img> был удалён из дерева\n```\n\n### Сбор всех ссылок\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### Обёртывание блоков кода в контейнер\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> теперь обёрнут внутри <div class=\"code-block\">\n```\n\n## Поведение\n\n- **Неизменяемость:** возвращается новое дерево; исходное не модифицируется\n- **Обход сверху вниз:** посетитель вызывается для родителя до посещения его потомков\n- **Замена:** если посетитель возвращает узел, он заменяет текущий узел до обхода его потомков\n- **Без изменений:** если посетитель возвращает `void` (или `undefined`), исходный узел сохраняется\n- **Рекурсия:** потомки узлов `\"root\"` и `\"element\"` обходятся рекурсивно",
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