extractLang()

import { extractLang } from "@unifast/core";

Signature

function extractLang(code: HastElement): string | null

Parameters

code

Returns

string | null — The language identifier extracted from the first language-* class, or null if no language class is found.

Usage

import { extractLang } from "@unifast/core";
import type { HastElement } from "@unifast/core";

const codeElement: HastElement = {
  type: "element",
  tagName: "code",
  properties: { className: ["language-typescript"] },
  children: [{ type: "text", value: "const x = 1;" }],
};

const lang = extractLang(codeElement);

console.log(lang);
// typescript

Examples

Extract language from a code element

import { extractLang } from "@unifast/core";
import type { HastElement } from "@unifast/core";

const code: HastElement = {
  type: "element",
  tagName: "code",
  properties: { className: ["language-js", "highlight"] },
  children: [{ type: "text", value: "console.log('hello');" }],
};

console.log(extractLang(code));
// js

When no language class exists

import { extractLang } from "@unifast/core";
import type { HastElement } from "@unifast/core";

const code: HastElement = {
  type: "element",
  tagName: "code",
  properties: { className: ["highlight"] },
  children: [{ type: "text", value: "plain text" }],
};

console.log(extractLang(code));
// null

When className is not an array

import { extractLang } from "@unifast/core";
import type { HastElement } from "@unifast/core";

const code: HastElement = {
  type: "element",
  tagName: "code",
  properties: {},
  children: [{ type: "text", value: "no classes" }],
};

console.log(extractLang(code));
// null

Using with findCodeChild

import { extractLang, findCodeChild } from "@unifast/core";
import type { HastElement } from "@unifast/core";

const pre: HastElement = {
  type: "element",
  tagName: "pre",
  properties: {},
  children: [
    {
      type: "element",
      tagName: "code",
      properties: { className: ["language-python"] },
      children: [{ type: "text", value: "print('hello')" }],
    },
  ],
};

const code = findCodeChild(pre);
if (code) {
  console.log(extractLang(code));
  // python
}