Transform Markdown Newlines into <br> Tags with mdast-util-newline-to-break

Do you need more control over how line breaks are rendered in your markdown? The mdast-util-newline-to-break utility offers a powerful way to convert standard line endings into HTML <br> tags directly within your markdown abstract syntax tree (AST). This is useful when you want to display user-authored content, replicating how platforms like GitHub manage line breaks in comments and issues.

This article dives into what mdast-util-newline-to-break is, when and how to use it, and why it matters for your markdown processing pipeline.

What is mdast-util-newline-to-break?

mdast-util-newline-to-break is a small but mighty utility designed to process markdown ASTs. It specifically targets newline characters (enters) and transforms them into explicit hard breaks represented by HTML <br> tags. This is achieved by adding mdast Break nodes to the syntax tree.

• Converts newline characters into <br> tags.
• Operates directly on the markdown AST.
• Simple API for seamless integration.

Why Use mdast-util-newline-to-break?

While markdown offers methods for creating hard breaks (trailing spaces or escapes), mdast-util-newline-to-break provides an alternative that can be more intuitive for users and can offer greater consistency in rendering.

Consider these scenarios:

• User-Generated Content: Displaying content as users intended, where a line ending should visually translate to a break.
• Simplified Authoring: Providing an easier way for users to create line breaks.
• Consistent Rendering: Ensuring consistent handling of line breaks across different markdown renderers.

Markdown provides two ways to include hard breaks by using trailing spaces or escapes:

lorem␠␠
ipsum

lorem \
ipsum

Installation

1. NPM: npm install mdast-util-newline-to-break
2. Deno: import { newlineToBreak } from 'https://esm.sh/mdast-util-newline-to-break@2'
3. Browsers: <script type="module"> import { newlineToBreak } from 'https://esm.sh/mdast-util-newline-to-break@2?bundle' </script>

This package is ESM only. In Node.js (version 16+), install with npm.

Usage: A Practical Example

Here's a simple example demonstrating how to use mdast-util-newline-to-break to transform a markdown file:

import fs from 'node:fs/promises'
import { fromMarkdown } from 'mdast-util-from-markdown'
import { newlineToBreak } from 'mdast-util-newline-to-break'
import { toMarkdown } from 'mdast-util-to-markdown'

async function processMarkdown(filePath) {
  const doc = await fs.readFile(filePath);
  const tree = fromMarkdown(doc); //creates a markdown abstract syntax tree
  newlineToBreak(tree); // appends <br> tags to the tree/ mdast
  const output = toMarkdown(tree); // returns to markdown

  console.log(output);
}

processMarkdown('example.md');

This example reads a markdown file (example.md), converts it to an AST using mdast-util-from-markdown, applies newlineToBreak to insert <br> elements, and then converts it back to markdown using mdast-util-to-markdown.

Diving Deeper: The API

The package exports a single identifier: newlineToBreak.

newlineToBreak(tree)

This function takes a markdown AST (tree) as input and modifies it in place, replacing newline characters with <br> elements.

• Parameter: tree (Node) - The markdown AST to modify.

mdast-util-newline-to-break and Syntaxes

This utility focuses on identifying and converting plain newline characters (\r, \n, and \r\n) within the markdown content. It seamlessly integrates with the existing markdown syntax by adding Break nodes, the same nodes used for breaks created with spaces or escapes.

Types & Compatibility

mdast-util-newline-to-break is fully typed with TypeScript, ensuring type safety and a better development experience. It is compatible with maintained versions of Node.js.

Security Considerations

Since mdast-util-newline-to-break operates on the AST and doesn't directly involve user content in a way that could lead to XSS attacks, it is considered secure to use.

Related Projects

• remark-breaks: A remark plugin that provides this utility for unified remark processing. Offers an easy way to integrate mdast-util-newline-to-break into your remark workflow.
• remark-gfm: Support GFM (autolink literals, footnotes, strikethrough, tables, tasklists)
• remark-github: Link references to commits, issues, and users, in the same way that GitHub does

By understanding and utilizing mdast-util-newline-to-break, you can gain finer control over how line breaks are rendered in your markdown, leading to a better user experience and more consistent content display.