import { unified } from "unified"
import remarkParse from "remark-parse"
import remarkStringify from "remark-stringify"
import remarkFrontmatter from "remark-frontmatter"
import remarkFrontmatterYaml from "remark-frontmatter-yaml"

const file = await unified()
    .use(remarkParse)
    .use(remarkStringify)
    .use(remarkFrontmatter)
    .use(remarkFrontmatterYaml)
    .process(/* content */)

console.log(file.data.frontmatter) // { message: "Hello, World!" }