{
  "url": "https://unifast.dev/zh-TW/docs/packages/core/extract-lang/",
  "locale": "zh-TW",
  "title": "extractLang()",
  "description": "從 code 元素的 className 中擷取程式語言識別字。",
  "section": "packages",
  "body": "```ts\nimport { extractLang } from \"@unifast/core\";\n```\n\n## 函式簽名\n\n```ts\nfunction extractLang(code: HastElement): string | null\n```\n\n## 參數\n\n### code\n\n| 屬性 | 型別 | 預設值 | 說明 |\n|----------|------|---------|-------------|\n| `type` | `\"element\"` | — | 節點型別識別字 |\n| `tagName` | `string` | — | HTML 標籤名稱（通常為 `\"code\"`） |\n| `properties` | `Record<string, unknown>` | — | 元素屬性，其中包含 `className` |\n| `children` | `HastNode[]` | — | 元素的子節點 |\n\n## 回傳值\n\n`string | null` — 從第一個 `language-*` class 中擷取出的語言識別字；若找不到語言 class 則為 `null`。\n\n## 用法\n\n```ts\nimport { extractLang } from \"@unifast/core\";\nimport type { HastElement } from \"@unifast/core\";\n\nconst codeElement: HastElement = {\n  type: \"element\",\n  tagName: \"code\",\n  properties: { className: [\"language-typescript\"] },\n  children: [{ type: \"text\", value: \"const x = 1;\" }],\n};\n\nconst lang = extractLang(codeElement);\n\nconsole.log(lang);\n// typescript\n```\n\n## 範例\n\n### 從 code 元素擷取語言\n\n```ts\nimport { extractLang } from \"@unifast/core\";\nimport type { HastElement } from \"@unifast/core\";\n\nconst code: HastElement = {\n  type: \"element\",\n  tagName: \"code\",\n  properties: { className: [\"language-js\", \"highlight\"] },\n  children: [{ type: \"text\", value: \"console.log('hello');\" }],\n};\n\nconsole.log(extractLang(code));\n// js\n```\n\n### 沒有語言 class 時\n\n```ts\nimport { extractLang } from \"@unifast/core\";\nimport type { HastElement } from \"@unifast/core\";\n\nconst code: HastElement = {\n  type: \"element\",\n  tagName: \"code\",\n  properties: { className: [\"highlight\"] },\n  children: [{ type: \"text\", value: \"plain text\" }],\n};\n\nconsole.log(extractLang(code));\n// null\n```\n\n### 當 className 並非陣列時\n\n```ts\nimport { extractLang } from \"@unifast/core\";\nimport type { HastElement } from \"@unifast/core\";\n\nconst code: HastElement = {\n  type: \"element\",\n  tagName: \"code\",\n  properties: {},\n  children: [{ type: \"text\", value: \"no classes\" }],\n};\n\nconsole.log(extractLang(code));\n// null\n```\n\n### 搭配 findCodeChild 使用\n\n```ts\nimport { extractLang, findCodeChild } from \"@unifast/core\";\nimport type { HastElement } from \"@unifast/core\";\n\nconst pre: HastElement = {\n  type: \"element\",\n  tagName: \"pre\",\n  properties: {},\n  children: [\n    {\n      type: \"element\",\n      tagName: \"code\",\n      properties: { className: [\"language-python\"] },\n      children: [{ type: \"text\", value: \"print('hello')\" }],\n    },\n  ],\n};\n\nconst code = findCodeChild(pre);\nif (code) {\n  console.log(extractLang(code));\n  // python\n}\n```",
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