Markdown

The SDK uses mdast (Markdown AST) as the canonical format for message formatting. Each adapter converts the AST to the platform's native format.

import {
  root, paragraph, text, strong, emphasis, strikethrough,
  inlineCode, codeBlock, link, blockquote,
  parseMarkdown, stringifyMarkdown, toPlainText, walkAst,
} from "chat";

Node builders

paragraph

A paragraph block.

paragraph([text("Hello "), strong([text("world")])])

text

Plain text node.

text("Hello, world!")

strong

Bold text.

strong([text("important")])

emphasis

Italic text.

emphasis([text("emphasized")])

strikethrough

~~Strikethrough~~ text.

strikethrough([text("removed")])

inlineCode

Inline code span.

inlineCode("const x = 1")

blockquote

Block quotation.

blockquote([paragraph([text("Quoted text")])])

Parsing and stringifying

parseMarkdown

Parse a markdown string into an mdast AST.

const ast = parseMarkdown("**Hello** world");

stringifyMarkdown

Convert an mdast AST back to a markdown string.

const md = stringifyMarkdown(ast); // "**Hello** world"

toPlainText

Strip all formatting and return plain text.

const plain = toPlainText(ast); // "Hello world"

markdownToPlainText

Shorthand for parsing markdown and extracting plain text.

const plain = markdownToPlainText("**Hello** world"); // "Hello world"

AST utilities

walkAst

Transform an AST by visiting each node. Return a new value to replace the node, or undefined to keep it unchanged.

const transformed = walkAst(ast, (node) => {
  if (isStrongNode(node)) {
    return emphasis(getNodeChildren(node));
  }
  return undefined;
});

Type guards

Functions for checking node types:

Guard	Matches
`isTextNode(node)`	Plain text
`isParagraphNode(node)`	Paragraph
`isStrongNode(node)`	Bold
`isEmphasisNode(node)`	Italic
`isDeleteNode(node)`	Strikethrough
`isInlineCodeNode(node)`	Inline code
`isCodeNode(node)`	Code block
`isLinkNode(node)`	Link
`isBlockquoteNode(node)`	Blockquote
`isListNode(node)`	List
`isListItemNode(node)`	List item

getNodeChildren / getNodeValue

Safely access node properties without type narrowing.

const children = getNodeChildren(node); // Content[] | undefined
const value = getNodeValue(node);       // string | undefined

The SDK uses mdast as the canonical format and each adapter converts it to the platform's native syntax. You write standard markdown and the SDK handles the translation — but it helps to know how each platform renders common formatting.

Feature	Slack	Teams	Google Chat
Bold	`text`	`text`	`text`
Italic	`_text_`	`_text_`	`_text_`
Strikethrough	`~text~`	`~~text~~`	`~text~`
Code	`code`	`code`	`code`
Code blocks	```	```	```
Links	`<url\|text>`	`[text](url)`	`[text](url)`
Lists	Supported	Supported	Supported
Blockquotes	`>`	`>`	Simulated with `>` prefix
Mentions	`<@USER>`	`<at>name</at>`	`<users/{id}>`

You don't need to worry about these differences when using the SDK — the AST builders and parseMarkdown handle conversion automatically. This table is useful if you're working with raw platform payloads or debugging formatting issues.