A code and code-diff prettyprinter for the terminal, powered by Shiki
npm install niftty
A nifty code syntax highlighter for the terminal, powered by Shiki.
Niftty is particularly good at:
- Rendering diffs, including:
- Collapsing common regions
- Highlighting words/characters changed in modified blocks
- Streaming code rewrites generated by an LLM
Known limitations:
- Requires a modern, xterm-256color-friendly shell.
Grab it with your favorite package manager:
``bash`
npm install niftty
`typescript
import { niftty } from "niftty";
process.stdout.write(
await niftty({
code: "let foo = 123;",
diffWith: "let foo = 456;", // remove to not render a diff
lang: "tsx", // or any shiki language
theme: "catppuccin-frappe", // or any shiki-friendly theme
lineNumbers: "both", // remove to hide line numbers
// collapseUnchanged: true // to collapse common blocks
// streaming: true // if you're streamin' from an LLM
})
);
`
Renders a code snippet using shiki, returning an ANSI-encoded string.
| Parameter | Type | Description |
|-----------|------|-------------|
| code | string | The code to render |theme
| | shiki.ThemeRegistration \| shiki.BundledTheme | Named theme or VSCode-compatible theme object |diffWith?
| | string | Code to diff against for showing additions/removals |lang?
| | shiki.BundledLanguage \| shiki.SpecialLanguage | Language for syntax highlighting (auto-detected from filePath if not provided) |filePath?
| | string | File path to help with language detection when lang is not specified |collapseUnchanged?
| | boolean \| Partial | Whether to collapse unchanged lines in diffs |streaming?
| | boolean \| number | Enable streaming mode for LLM code generation. Number customizes window size |highlighter?
| | shiki.Highlighter | Reuse a shiki highlighter instance for better performance |lineNumbers?
| | boolean \| "both" | Show line numbers. Use "both" for old and new line numbers in diffs |
If you're building a coding agent and streaming code from an LLM, and want to show that, turn on streaming mode, and feed in the original code (diffWith and the partial currently-emitted code. Niftty will render an on-the-fly diff.
`typescript``
niftty({
// ...
streaming: true // or a number (e.g. 10) for a window of that size
highlighter: myHighlighter // re-use a shiki instance
// ...
});
That looks like this:
Any VSCode- or shiki-compatible theme should work on modern shells.
Brought to you with 💜 from New York.