vterm.js

Modern terminal emulator — full VT/ECMA-48/xterm standards coverage. Pure TypeScript, zero dependencies.

Part of the vterm monorepo.

Features

• All SGR attributes — bold, faint, italic, blink, overline, strikethrough, inverse, hidden
• Underline styles — single, double, curly, dotted, dashed (SGR 4:0–4:5)
• Full color support — 16-color, 256-color, 24-bit truecolor for foreground, background, and underline
• Cursor shapes — block, underline, bar with blinking variants (DECSCUSR)
• Cursor control — CUP, CUU/CUD/CUF/CUB, CHA, CNL, CPL, HVP, save/restore (DECSC/DECRC)
• Erase operations — ED 0/1/2/3, EL 0/1/2, ECH
• Editing operations — ICH, DCH, IL, DL, REP (repeat last character)
• Scroll regions — DECSTBM, SU, SD with content preservation
• DEC private modes — alternate screen, auto-wrap, origin, insert, reverse video, bracketed paste
• Mouse tracking — X10, normal, button, any-event, SGR format
• Focus tracking — mode 1004
• Synchronized output — mode 2026
• Application cursor keys & keypad
• OSC sequences — window title (OSC 0/2), hyperlinks (OSC 8), clipboard (OSC 52), colors
• DCS sequences — consumed and ignored, XTVERSION response
• Device attributes — DA1/DA2/DA3 responses
• Device status reports — DSR responses
• Mode reporting — DECRPM
• Character sets — DEC Special Graphics (box drawing), UTF-8
• Soft terminal reset — DECSTR
• Scrollback buffer with configurable limit
• Wide character support — CJK, emoji ZWJ sequences, regional indicators, VS-16
• Full C0/C1 control code handling
• Zero dependencies — works in Bun, Node.js, and browsers

Install

npm install vterm.js

Usage

Basic

import { createVtermScreen } from "vterm.js"

const screen = createVtermScreen({ cols: 80, rows: 24 })
screen.process(new TextEncoder().encode("Hello, \x1b[1mBold\x1b[0m World!"))

console.log(screen.getText()) // "Hello, Bold World!"
console.log(screen.getCell(0, 7).bold) // true

Cursor shapes

// Set cursor to blinking bar
screen.process(new TextEncoder().encode("\x1b[5 q"))
console.log(screen.getCursorShape()) // "bar"
console.log(screen.getCursorBlinking()) // true

Hyperlinks (OSC 8)

screen.process(new TextEncoder().encode("\x1b]8;;https://example.com\x1b\\Click here\x1b]8;;\x1b\\"))
console.log(screen.getCell(0, 0).url) // "https://example.com"

Device attribute responses

const screen = createVtermScreen({
  cols: 80,
  rows: 24,
  onResponse: (data) => {
    // Write response back to PTY
    pty.write(data)
  },
})

// When the screen receives DA1 (\x1b[c), it calls onResponse
// with the appropriate response string

Extended SGR

// Bold + curly underline + truecolor orange foreground + underline color
screen.process(new TextEncoder().encode("\x1b[1;4:3;38;2;255;100;0;58;2;0;150;255mStyled\x1b[0m"))

const cell = screen.getCell(0, 0)
console.log(cell.bold) // true
console.log(cell.underline) // "curly"
console.log(cell.fg) // { r: 255, g: 100, b: 0 }
console.log(cell.underlineColor) // { r: 0, g: 150, b: 255 }

API

createVtermScreen(options)

| Option | Type | Default | Description | | ----------------- | ------------------------ | ------- | ---------------------------------- | | cols | number | 80 | Terminal width | | rows | number | 24 | Terminal height | | scrollbackLimit | number | 1000 | Max scrollback lines | | onResponse | (data: string) => void | — | Callback for DA1/DA2/DSR responses |

Screen methods

| Method | Description | | ------------------------------ | ------------------------------------------------------ | | process(data: Uint8Array) | Feed raw terminal data | | getText() | Get all text (scrollback + screen) | | getTextRange(sr, sc, er, ec) | Get text in a range | | getLine(row) | Get cells for a row | | getCell(row, col) | Get a single cell | | getCursorPosition() | Get cursor { x, y } | | getCursorVisible() | Check cursor visibility | | getCursorShape() | Get cursor shape: "block", "underline", or "bar" | | getCursorBlinking() | Check if cursor is blinking | | getMode(mode) | Check terminal mode | | getTitle() | Get window title | | getScrollbackLength() | Number of scrollback lines | | getViewportOffset() | Current viewport scroll offset | | scrollViewport(delta) | Scroll viewport | | resize(cols, rows) | Resize terminal | | reset() | Reset to initial state |

Cell properties

interface ScreenCell {
  char: string
  fg: CellColor | null // { r, g, b }
  bg: CellColor | null
  bold: boolean
  faint: boolean
  italic: boolean
  underline: "none" | "single" | "double" | "curly" | "dotted" | "dashed"
  underlineColor: CellColor | null
  overline: boolean
  strikethrough: boolean
  inverse: boolean
  hidden: boolean
  blink: boolean
  wide: boolean
  url: string | null // OSC 8 hyperlink
}

vs vt100.js

| Feature | vt100.js | vterm.js | | -------------------------------------------- | -------- | -------- | | SGR basics (bold, italic, underline, colors) | Yes | Yes | | Underline styles (curly, dotted, dashed) | Yes | Yes | | Underline color | No | Yes | | Blink, overline | No | Yes | | Cursor shapes (DECSCUSR) | No | Yes | | OSC 8 hyperlinks | No | Yes | | DA1/DA2/DA3 responses | No | Yes | | DSR/DECRPM responses | No | Yes | | Mouse tracking | No | Yes | | Focus tracking | No | Yes | | Synchronized output | No | Yes | | DEC Special Graphics | No | Yes | | REP (repeat character) | No | Yes | | DECSTR (soft reset) | No | Yes | | DCS sequences | No | Yes | | Package size | Smaller | Larger |

Use vt100.js when you want fast and simple — it covers ~90% of real-world terminal usage.

Use vterm.js when you need everything — 100% coverage of the terminfo.dev feature matrix.

See also

• vt100.js — VT100-era emulator (smaller, focused)
• Termless — headless terminal testing
• Terminfo.dev — terminal feature support tables

License

MIT