Terminal

Terminal is a passive scrolling log view — a place to stream program output, log lines, or command results into. You feed it with write / writeLine; it keeps the most recent output in a fixed-capacity ring buffer and shows the newest lines at the bottom. It is not focusable and takes no keyboard input; scroll-back is mouse-wheel only, and any new write snaps the view back to the newest line. Incoming text is sanitized as it is drawn, so untrusted output can't corrupt the screen.

Usage

import { Group, Terminal, terminalWriter } from '@jsvision/ui';

const group = new Group();
const log = new Terminal({ capacity: 8000 });
log.layout = { position: 'absolute', rect: { x: 0, y: 0, width: 60, height: 10 } };
group.add(log);

log.writeLine('Build started...');
log.write('compiling');
log.write('.'.repeat(3) + '\n');
log.writeLine('Done.');

// Wrap it as a plain (text) => void sink for anything that streams strings:
const write = terminalWriter(log);
write('server listening on :8080\n');
// childProcess.stdout.on('data', (chunk) => write(String(chunk)));

Live example

🚧 Live demo coming soon

An interactive, in-browser demo of Terminal lands in a later update. Until then, the reference below covers its full API.

Props

new Terminal(options).

Prop	Type	Default	Description
capacity	number	32000	Scroll-back retained, in UTF-16 code units. Older lines are dropped.

Methods

Member	Description
write(text)	Append raw text; snaps the view back to the bottom.
writeLine(text)	Append one line (adds the trailing newline).
clear()	Drop all content.
terminalWriter(term)	Standalone helper: wraps a Terminal as a (text) => void callback sink.

Keyboard & mouse

Input	Result
Wheel up	Scroll back through history (3 lines per notch).
Wheel down	Scroll forward toward the newest line.
Any write	Jumps back to the bottom (pinned to the newest line).

Mouse buttons and keyboard keys are inert — this is a passive output sink.

Sizing & layout

Give it an absolute rect (or a flex size). It shows the newest lines that fit the height, pinned to the bottom; a wheel-up offsets that window upward until the oldest retained line, then stops.

Best practices

• Stream through terminalWriter. It adapts the view to the (text) => void shape a logger, a subprocess stdout handler, or a progress reporter already expects.
• Size capacity to the workload. The ring is bounded — a chatty build log wants more than the default; a short status feed wants less.
• Don't sanitize upstream. Every cell is sanitized at draw time, so it is safe to pipe raw, possibly-hostile process output straight in.

Theming

Lines are drawn in the terminalNormal role.

Related

• Surface view — a scrollable window onto an offscreen canvas.
• List box — a focusable, selectable single-column list.
• API reference — the generated Terminal signature.