# markdown-wasm

Very fast Markdown parser & HTML renderer implemented in WebAssembly

- Zero dependencies
- Portable
- Simple API
- Fast and efficient

Based on [md4c](http://github.com/mity/md4c)


## Examples

In Nodejs

```js
const markdown = require("./dist/markdown.node.js")
console.log(markdown.parse("# hello\n*world*"))
```

ES module

```js
import * as markdown from "./dist/markdown.es"
console.log(markdown.parse("# hello\n*world*"))
```

Separately loded wasm module (useful in web browsers)

```js
require("./dist/markdown").ready.then(markdown => {
  console.log(markdown.parse("# hello\n*world*"))
})
```


## Install

```
npm install markdown-wasm
```


## API

```ts
/**
 * parse reads markdown source at s and converts it to HTML.
 * When output is a byte array, it will be a reference.
 */
export function parse(s :Source, o? :ParseOptions & { asMemoryView? :never|false }) :string
export function parse(s :Source, o? :ParseOptions & { asMemoryView :true }) :Uint8Array

/** Markdown source code can be provided as a JavaScript string or UTF8 encoded data */
type Source = string|ArrayLike<number>

/** Options for the parse function */
export interface ParseOptions {
  /**
   * Customize parsing.
   * If not provided, the following flags are used, equating to github-style parsing:
   *   COLLAPSE_WHITESPACE
   *   PERMISSIVE_ATX_HEADERS
   *   PERMISSIVE_URL_AUTO_LINKS
   *   STRIKETHROUGH
   *   TABLES
   *   TASK_LISTS
   */
  parseFlags? :ParseFlags

  /**
   * asMemoryView=true causes parse() to return a view of heap memory as a Uint8Array,
   * instead of a string.
   *
   * The returned Uint8Array is only valid until the next call to parse().
   * If you need to keep the returned data around, call Uint8Array.slice() to make a copy,
   * as each call to parse() uses the same underlying memory.
   *
   * This only provides a performance benefit when you never need to convert the output
   * to a string. In most cases you're better off leaving this unset or false.
   */
  asMemoryView? :boolean
}

/** Flags that customize Markdown parsing */
export enum ParseFlags {
  /** In TEXT, collapse non-trivial whitespace into single ' ' */ COLLAPSE_WHITESPACE,
  /** Enable $ and $$ containing LaTeX equations. */              LATEX_MATH_SPANS,
  /** Disable raw HTML blocks. */                                 NO_HTML_BLOCKS,
  /** Disable raw HTML (inline). */                               NO_HTML_SPANS,
  /** Disable indented code blocks. (Only fenced code works.) */  NO_INDENTED_CODE_BLOCKS,
  /** Do not require space in ATX headers ( ###header ) */        PERMISSIVE_ATX_HEADERS,
  /** Recognize e-mails as links even without <...> */            PERMISSIVE_EMAIL_AUTO_LINKS,
  /** Recognize URLs as links even without <...> */               PERMISSIVE_URL_AUTO_LINKS,
  /** Enable WWW autolinks (without proto; just 'www.') */        PERMISSIVE_WWW_AUTOLINKS,
  /** Enable strikethrough extension. */                          STRIKETHROUGH,
  /** Enable tables extension. */                                 TABLES,
  /** Enable task list extension. */                              TASK_LISTS,
  /** Enable wiki links extension. */                             WIKI_LINKS,

  /** Default flags */                                            DEFAULT,
  /** Shorthand for NO_HTML_BLOCKS | NO_HTML_SPANS */             NO_HTML,
}
```

See `markdown.d.ts`


## Building from source

```
npm install
npx wasmc
```

Build debug version of markdown-es into ./build/debug and watch source files:

```
npx wasmc -g -w
```