xterm-go

A Go port of xterm.js 6.0.0 — a terminal emulator library, compiled to WebAssembly for the browser. The VT core is pure Go and also works headless on any platform.

Live demo — a wasm terminal with an in-browser echo shell.

xterm.js is the front-end terminal component used by VS Code, Hyper and Theia — and by skywire's web pty. This port reimplements it as a Go library so Go/wasm applications can embed a full terminal without JavaScript dependencies.

Features

• Terminal apps just work: the full escape-sequence machinery of xterm.js is ported — cursor addressing, scroll regions, the alternate screen buffer, insert/delete, SGR text styling (16/256/truecolor, underline styles), charsets, device reports (DA/DSR/DECRQM/DECRQSS) and mouse tracking (X10/VT200/DRAG/ANY with SGR encoding) for curses apps.
• Headless-capable core: the vt subpackage (parser, buffers, input handler) is pure Go with zero dependencies — it builds natively, so terminal semantics are tested with plain go test, no browser needed. Use it standalone to interpret pty output server-side.
• Rich Unicode support: CJK wide characters, combining characters, wcwidth tables ported from the UnicodeV6 provider.
• Scrollback: ring-buffer scrollback with reflow on resize, native scrollbar viewport in the browser layer.
• Self-contained: no JS dependencies; styles are injected automatically.
• GPU-accelerated: an optional WebGL2 renderer (the addon-webgl equivalent) draws the grid as instanced quads sampling a glyph texture atlas, with pixel-perfect procedural box drawing, block, shade and powerline glyphs. Enable with term.EnableWebGL(); it falls back to the DOM renderer when WebGL2 is unavailable.
• IME support: composition events (CJK input methods, dead keys) are handled with an in-place composition view like xterm.js.
• Small: ~850 KB wasm with TinyGo (≈4 MB with standard Go).

What xterm-go is not

• xterm-go is not a terminal application you can download and use — it is a library for embedding terminals into (wasm) applications.
• xterm-go is not bash. Connect it to a real process over a WebSocket (see Attach) or feed it output yourself.

Getting Started

go get github.com/0magnet/xterm-go

Create a <div id="terminal"></div> in your page, then in your wasm program:

//go:build js && wasm

package main

import (
	"syscall/js"

	xterm "github.com/0magnet/xterm-go"
	"github.com/0magnet/xterm-go/vt"
)

func main() {
	term := xterm.New(nil) // nil = default options
	term.Open(js.Global().Get("document").Call("getElementById", "terminal"))
	term.Fit() // size to the parent element

	term.WriteString("Hello from \x1b[1;3;31mxterm-go\x1b[0m $ ")
	term.Core.OnData = func(data string) {
		term.WriteString(data) // echo
	}

	select {}
}

Build with standard Go or TinyGo:

GOOS=js GOARCH=wasm go build -o main.wasm .
# or ~6x smaller:
tinygo build -target wasm -no-debug -o main.wasm .

Options

xterm.New takes *vt.Options (pass nil for defaults): dimensions, scrollback length, fonts, cursor style/blink, a Theme with the standard 16 colors, and more — mirroring the xterm.js options relevant to the port.

opts := vt.NewOptions()
opts.Scrollback = 5000
opts.FontSize = 14
opts.Theme.Background = "#1e1e2e"
term := xterm.New(opts)

Connecting to a pty (attach)

The equivalent of @xterm/addon-attach is built in — hand it a WebSocket carrying pty data:

ws := js.Global().Get("WebSocket").New("wss://example.com/pty")
term.Attach(ws, true) // bidirectional: keystrokes go back over the socket

Fitting (fit addon)

term.Fit() resizes the terminal to fill its parent element; call it from a window resize listener.

Headless use

The vt package runs anywhere Go runs:

term := vt.NewTerminal(nil)
term.WriteString("ls\r\n\x1b[1;34mdocs\x1b[0m  main.go\r\n")
line := term.Buffer().Lines.Get(1).TranslateToString(true, 0, -1)
// "docs  main.go"

Real-world uses

• Building the web terminal for skywire's wasm hypervisor UI, replacing the bundled xterm.js + fit/attach/webgl addons.

WebGL renderer

if err := term.EnableWebGL(); err != nil {
	// WebGL2 unavailable — the DOM renderer stays active
}
// term.DisableWebGL() switches back

Differences from xterm.js

• Parser handlers are synchronous (Go has no reason for the async parse-stack machinery).
• The WebGL renderer uses a single 2048² atlas page (cleared and lazily rebuilt on overflow) instead of the multi-page grow/merge machinery, and does not port the selection/decoration/ligature-joiner model overrides or the minimum-contrast-ratio option.
• The deprecated canvas renderer is not ported (DOM and WebGL are).
• Accessibility tree, link decorations and the selection service are not (yet) ported; text selection uses the browser's native selection (DOM renderer).
• Windows conpty wrapping heuristics are not ported.

Contributing

Issues and PRs welcome at github.com/0magnet/xterm-go.

License

Copyright (c) 2017-2022, The xterm.js authors (MIT License)
Copyright (c) 2014-2016, SourceLair Private Company (MIT License)
Copyright (c) 2012-2013, Christopher Jeffrey (MIT License)
Go port copyright (c) 2026 (MIT License)

Dependency Graph

Made with goda:

# GOOS=js: the import edges of a wasm program live in js/wasm-tagged
# files and are invisible to a host-context run
GOOS=js GOARCH=wasm go run github.com/loov/goda@latest graph github.com/0magnet/xterm-go/... | dot -Tsvg -o docs/xterm-go-goda-graph.svg

Lines of Code

Made with gocloc (excludes vendor/, node_modules/, .git/):

gocloc --not-match-d='(vendor|node_modules|\.git)' .

-------------------------------------------------------------------------------
Language                     files          blank        comment           code
-------------------------------------------------------------------------------
Go                              36           1201           1535          11108
JavaScript                       1             56             46            457
Markdown                         1             40              0             93
YAML                             1              0              9             69
HTML                             1              0              0             30
JSON                             2              0              0             28
-------------------------------------------------------------------------------
TOTAL                           42           1297           1590          11785
-------------------------------------------------------------------------------