Function writeMarkdownFile

writeMarkdownFile(
parsedMarkdown: ParsedMarkdown,
outputFilename: string,
): Promise<void>
Writes a ParsedMarkdown object to a file with YAML frontmatter.

Serializes the frontmatter object to YAML format, wraps it in --- delimiters, and combines it with the markdown content before writing to the specified file. If frontmatter is empty, only content is written.
Parameters
- parsedMarkdown: ParsedMarkdown
  Object containing frontmatter and content to write
- outputFilename: string
  Path where the markdown file should be written
Returns Promise<void>
Promise that resolves when file is successfully written
Throws
Error if file write fails
Example
Write markdown with frontmatter
```
const document = {
  frontMatter: {
    title: "My Article",
    date: "2025-12-03",
    tags: ["typescript", "markdown"]
  },
  content: "# Hello World\n\nThis is my content."
};

await writeMarkdownFile(document, "./output/article.md");

Creates this file:
---
title: My Article
date: '2025-12-03'
tags:
  - typescript
  - markdown
---
# Hello World
This is my content.
```
Example
Write content-only markdown
```
await writeMarkdownFile(
  { frontMatter: {}, content: "# Just content" },
  "simple.md"
);
```
- Defined in markdown.ts:376