Code Highlighting

The @streamdown/code plugin provides syntax highlighting powered by Shiki. It supports 100+ programming languages and multiple colour themes.

Overview

Code blocks in your markdown are automatically highlighted when the code plugin is enabled. Simply specify the language after the opening triple backticks:

markdown

```typescript
const greeting: string = "G'day, world!"
console.log(greeting)
```

Rendered output

typescript

const greeting: string = "G'day, world!"console.log(greeting)

Supported languages

The code plugin supports all languages that Shiki supports, including:

TypeScript

JavaScript

Python

Rust

Java

C/C++

Ruby

PHP

Swift

Kotlin

SQL

CSS

HTML

Bash

JSON

YAML

TOML

Markdown

GraphQL

Dockerfile

Themes

Choose from Shiki's extensive theme library. You can specify different themes for light and dark modes:

Theme configuration

import { createCodePlugin } from "@streamdown/code"

const code = createCodePlugin({
  themes: ["github-light", "github-dark"],
  // Or use a single theme
  // theme: "one-dark-pro",
})

Popular themes include:

Theme	Style
`github-light`	GitHub's light theme
`github-dark`	GitHub's dark theme
`one-dark-pro`	Atom One Dark
`vitesse-light`	Vitesse light theme
`dracula`	Dracula colour scheme

Configuration

Full configuration

import { createCodePlugin } from "@streamdown/code"

const code = createCodePlugin({
  // Dual theme (light/dark)
  themes: ["github-light", "github-dark"],

  // Default language when none specified
  defaultLanguage: "typescript",

  // Show line numbers
  showLineNumbers: false,

  // Highlight specific lines
  highlightLines: true,
})

Streaming behaviour

During streaming, the code plugin uses a lightweight renderer that applies basic formatting without full syntax analysis. Once the code block is complete (closing backticks received), it switches to full Shiki highlighting.

No flicker during streaming

The transition from lightweight to full highlighting is seamless. Streamdown buffers the transition to prevent visual flicker.