Core Patterns
Composition Patterns
Imperative Composition
Create renderables and compose with .add():
import { createCliRenderer, BoxRenderable, TextRenderable } from "@opentui/core"
const renderer = await createCliRenderer()
// Create parent
const container = new BoxRenderable(renderer, {
id: "container",
flexDirection: "column",
padding: 1,
})
// Create children
const header = new TextRenderable(renderer, {
id: "header",
content: "Header",
fg: "#00FF00",
})
const body = new TextRenderable(renderer, {
id: "body",
content: "Body content",
})
// Compose tree
container.add(header)
container.add(body)
renderer.root.add(container)Declarative Composition (Constructs)
Use VNode functions for cleaner composition:
import { createCliRenderer, Box, Text, Input, delegate } from "@opentui/core"
const renderer = await createCliRenderer()
// Compose as function calls
const ui = Box(
{ flexDirection: "column", padding: 1 },
Text({ content: "Header", fg: "#00FF00" }),
Box(
{ flexDirection: "row", gap: 2 },
Text({ content: "Name:" }),
Input({ id: "name", placeholder: "Enter name..." }),
),
)
renderer.root.add(ui)Reusable Components
Create factory functions for reusable UI pieces:
// Imperative factory
function createLabeledInput(
renderer: RenderContext,
props: { id: string; label: string; placeholder: string }
) {
const container = new BoxRenderable(renderer, {
id: `${props.id}-container`,
flexDirection: "row",
gap: 1,
})
container.add(new TextRenderable(renderer, {
id: `${props.id}-label`,
content: props.label,
}))
container.add(new InputRenderable(renderer, {
id: `${props.id}-input`,
placeholder: props.placeholder,
width: 20,
}))
return container
}
// Declarative factory
function LabeledInput(props: { id: string; label: string; placeholder: string }) {
return delegate(
{ focus: `${props.id}-input` },
Box(
{ flexDirection: "row", gap: 1 },
Text({ content: props.label }),
Input({
id: `${props.id}-input`,
placeholder: props.placeholder,
width: 20,
}),
),
)
}Focus Delegation
Route focus calls to nested elements:
import { delegate, Box, Input, Text } from "@opentui/core"
const form = delegate(
{
focus: "email-input", // Route .focus() to this child
blur: "email-input", // Route .blur() to this child
},
Box(
{ border: true, padding: 1 },
Text({ content: "Email:" }),
Input({ id: "email-input", placeholder: "you@example.com" }),
),
)
// This focuses the input inside, not the box
form.focus()Event Handling
Keyboard Events
const renderer = await createCliRenderer()
// Global keyboard handler
renderer.keyInput.on("keypress", (key) => {
if (key.name === "escape") {
renderer.destroy()
process.exit(0)
}
if (key.ctrl && key.name === "c") {
// Ctrl+C handling (if exitOnCtrlC is false)
}
if (key.name === "tab") {
// Tab navigation
focusNext()
}
})
// Paste events
renderer.keyInput.on("paste", (event) => {
const text = decodePasteBytes(event.bytes)
currentInput?.setValue(currentInput.value + text)
})Component Events
import { InputRenderable, InputRenderableEvents } from "@opentui/core"
const input = new InputRenderable(renderer, {
id: "search",
placeholder: "Search...",
})
input.on(InputRenderableEvents.CHANGE, (value) => {
performSearch(value)
})
// Select events
const select = new SelectRenderable(renderer, {
id: "menu",
options: [...],
})
select.on(SelectRenderableEvents.ITEM_SELECTED, (index, option) => {
handleSelection(option)
})
select.on(SelectRenderableEvents.SELECTION_CHANGED, (index, option) => {
showPreview(option)
})Mouse Events
const button = new BoxRenderable(renderer, {
id: "button",
border: true,
onMouseDown: (event) => {
button.setBackgroundColor("#444444")
},
onMouseUp: (event) => {
button.setBackgroundColor("#222222")
handleClick()
},
onMouseMove: (event) => {
// Hover effect
},
})State Management
Local State
Manage state in closures or objects:
// Closure-based state
function createCounter(renderer: RenderContext) {
let count = 0
const display = new TextRenderable(renderer, {
id: "count",
content: `Count: ${count}`,
})
const increment = () => {
count++
display.setContent(`Count: ${count}`)
}
return { display, increment }
}
// Class-based state
class CounterWidget {
private count = 0
private display: TextRenderable
constructor(renderer: RenderContext) {
this.display = new TextRenderable(renderer, {
id: "count",
content: this.formatCount(),
})
}
private formatCount() {
return `Count: ${this.count}`
}
increment() {
this.count++
this.display.setContent(this.formatCount())
}
getRenderable() {
return this.display
}
}Focus Management
Track and manage focus across components:
class FocusManager {
private focusables: Renderable[] = []
private currentIndex = 0
register(renderable: Renderable) {
this.focusables.push(renderable)
}
focusNext() {
this.focusables[this.currentIndex]?.blur()
this.currentIndex = (this.currentIndex + 1) % this.focusables.length
this.focusables[this.currentIndex]?.focus()
}
focusPrevious() {
this.focusables[this.currentIndex]?.blur()
this.currentIndex = (this.currentIndex - 1 + this.focusables.length) % this.focusables.length
this.focusables[this.currentIndex]?.focus()
}
}
// Usage
const focusManager = new FocusManager()
focusManager.register(input1)
focusManager.register(input2)
focusManager.register(select1)
renderer.keyInput.on("keypress", (key) => {
if (key.name === "tab") {
key.shift ? focusManager.focusPrevious() : focusManager.focusNext()
}
})Lifecycle Patterns
Cleanup
Always clean up resources:
const renderer = await createCliRenderer()
// Track intervals/timeouts
const intervals: Timer[] = []
intervals.push(setInterval(() => {
updateClock()
}, 1000))
// Cleanup on exit
process.on("SIGINT", () => {
intervals.forEach(clearInterval)
renderer.destroy()
process.exit(0)
})
// Or use onDestroy callback
const renderer = await createCliRenderer({
onDestroy: () => {
intervals.forEach(clearInterval)
},
})Dynamic Updates
Update UI based on external data:
async function createDashboard(renderer: RenderContext) {
const statsText = new TextRenderable(renderer, {
id: "stats",
content: "Loading...",
})
// Poll for updates
const updateStats = async () => {
const data = await fetchStats()
statsText.setContent(`CPU: ${data.cpu}% | Memory: ${data.memory}%`)
}
// Initial load
await updateStats()
// Periodic updates
setInterval(updateStats, 5000)
return statsText
}Layout Patterns
Responsive Layout
Adapt to terminal size:
const renderer = await createCliRenderer()
const mainPanel = new BoxRenderable(renderer, {
id: "main",
width: "100%",
height: "100%",
flexDirection: renderer.width > 80 ? "row" : "column",
})
// Listen for resize
process.stdout.on("resize", () => {
mainPanel.setFlexDirection(renderer.width > 80 ? "row" : "column")
})Split Panels
function createSplitView(renderer: RenderContext, ratio = 0.3) {
const container = new BoxRenderable(renderer, {
id: "split",
flexDirection: "row",
width: "100%",
height: "100%",
})
const left = new BoxRenderable(renderer, {
id: "left",
width: `${ratio * 100}%`,
border: true,
})
const right = new BoxRenderable(renderer, {
id: "right",
flexGrow: 1,
border: true,
})
container.add(left)
container.add(right)
return { container, left, right }
}Debugging Patterns
Console Overlay
Use the built-in console for debugging:
const renderer = await createCliRenderer({
consoleOptions: {
startInDebugMode: true,
},
})
// Show console
renderer.console.show()
// All console methods work
console.log("Debug info")
console.warn("Warning")
console.error("Error")
// Toggle with keyboard
renderer.keyInput.on("keypress", (key) => {
if (key.name === "f12") {
renderer.console.toggle()
}
})State Inspection
function debugState(label: string, state: unknown) {
console.log(`[${label}]`, JSON.stringify(state, null, 2))
}
// In your update logic
debugState("form", { name: nameInput.value, email: emailInput.value })