# @expressive-code/core
The core package of [Expressive Code](https://expressive-code.com/), an engine for presenting source code on the web.
## Documentation
[Read the Expressive Code docs](https://expressive-code.com/) to learn more about the features provided by Expressive Code.
## When should I use this?
Using this core package directly is **only recommended for advanced use cases**.
Unless you're a plugin or integration author, you should probably use a higher-level package like [`astro-expressive-code`](https://www.npmjs.com/package/astro-expressive-code) or [`rehype-expressive-code`](https://www.npmjs.com/package/rehype-expressive-code) instead of this one.
## Installation
```bash
npm install @expressive-code/core
```
## Usage example
```js
// File: generate-html-core.mjs
import { ExpressiveCodeEngine } from '@expressive-code/core'
import { toHtml } from '@expressive-code/core/hast'
import fs from 'fs'
const ec = new ExpressiveCodeEngine({
plugins: [
// Add your plugins here
],
})
// Get base styles that should be included on the page
// (they are independent of the rendered code blocks)
const baseStyles = await ec.getBaseStyles()
const themeStyles = await ec.getThemeStyles()
const jsModules = await ec.getJsModules()
const renderResult = await ec.render({
code: 'console.log("Hello world!")',
language: 'js',
meta: '',
})
// Output results to the console
console.dir({
baseStyles,
themeStyles,
blockStyles: renderResult.styles,
htmlContent: toHtml(renderResult.renderedGroupAst),
})
// Convert the rendered AST to HTML
let htmlContent = toHtml(renderResult.renderedGroupAst)
// Collect styles and add them before the HTML content
const stylesToPrepend = []
stylesToPrepend.push(baseStyles)
stylesToPrepend.push(themeStyles)
stylesToPrepend.push(...renderResult.styles)
const styleContent = ``
const jsContent = ``
const htmlDocument = `
Document
${styleContent}
${jsContent}
${htmlContent}
`
// Output HTML to the console
console.log(htmlDocument)
// Run `node generate-html.mjs` to generate the HTML file
// and open it in the browser
fs.writeFileSync('index.html', htmlDocument)
```