Real-time / streaming
WebSocket-style live order stream with delta merge, out-of-order safety, pause / backlog, disconnect-reconnect, throughput slider.
A live, editable Svelte 5 data grid example from the SvGrid gallery (Real-time & Streaming). See the SvGrid documentation for the full API.
About this example
A live order-operations view in the Svelte 5 data grid fed by a WebSocket-style event stream: order.created adds a row at the top, order.updated merges in place with a field-level flash and order.cancelled marks the row for two seconds before dropping it. Rows are keyed by id so virtualization keeps scroll steady, every event carries seq and rowVersion so late events for a newer row are ignored, Pause buffers a backlog that Resume drains in order, a simulated disconnect shows reconnecting state, and a slider runs the stream from 1 to 50 events per second. Priority and Notes stay editable client-side.
A live order-ops view fed by a WebSocket-style event stream. The grid mounts with a small backlog, then pushed events flow in:
order.created→ new row at the toporder.updated→ in-place merge with a brief field-level flashorder.cancelled→ row marked as cancelled (kept visible for two seconds so the operator can see what changed, then dropped)
Things this demo is built to surface for an enterprise buyer:
1. Stable identity. Rows are keyed by order id, so virtualisation keeps scroll position rock-steady when a delta lands. No "jumping" rows.
2. Out-of-order safety. Each event carries seq + rowVersion. A late event for an already-newer row is ignored, the standard enterprise streaming-merge guarantee.
3. Pause / resume with backlog. Hitting Pause stops applying deltas but the stream keeps buffering. The KPI strip shows the backlog count growing; Resume drains it in order.
4. Disconnect / reconnect. The simulator can drop the connection for a configurable interval. The status pill flips through open → reconnecting → open, and the gap in the event log stays visible so the operator knows what they missed.
5. Throughput control. Slider runs the stream from a calm 1 event / sec up to a 50 event / sec firehose - shows the grid stays smooth at the high end.
Editable columns (Priority, Notes) live entirely client-side; the stream never overwrites them, so there's no merge conflict to resolve at the cell level. Onboarding edits to the wire would be a call to the same onCellValueChange callback the demo already wires up.
Imports, features and API used
Imports: @svgrid/grid, ../shared/stream-sim, ../shared/mock-api
Table features registered: rowSortingFeature, columnFilteringFeature
Frequently asked questions
How are out-of-order events handled?
Each event carries a rowVersion; the merge compares it with the version on the existing row and ignores anything older, which is the standard guarantee for a streaming merge.
What happens during Pause?
Events keep arriving into a buffer and the KPI strip shows the backlog count. Resume applies them in sequence order, so the grid ends in the same state as if it had never paused.
Can the stream overwrite a user's edits?
No. Priority and Notes are edited locally and never included in the stream's patches, so there is no merge conflict at the cell level; sending them to the server would be a call from onCellValueChange.
Related documentation
Related articles
- Real-Time Grids - Live WebSocket Updates in SvGrid - How to wire a high-frequency WebSocket feed into SvGrid without frame drops - covering stable row identity, RAF batching, and flash feedback done right.
Source code (34-realtime-orders.svelte)
<script lang="ts">
/**
* 34. Real-time / streaming - Order operations
* --------------------------------------------
* A live order-ops view fed by a WebSocket-style event stream. The
* grid mounts with a small backlog, then pushed events flow in:
*
* - `order.created` → new row at the top
* - `order.updated` → in-place merge with a brief field-level flash
* - `order.cancelled` → row marked as cancelled (kept visible for
* two seconds so the operator can see what changed, then dropped)
*
* Things this demo is built to surface for an enterprise buyer:
*
* 1. Stable identity. Rows are keyed by order id, so virtualisation
* keeps scroll position rock-steady when a delta lands. No
* "jumping" rows.
*
* 2. Out-of-order safety. Each event carries `seq` + `rowVersion`.
* A late event for an already-newer row is ignored, the standard
* enterprise streaming-merge guarantee.
*
* 3. Pause / resume with backlog. Hitting Pause stops applying
* deltas but the stream keeps buffering. The KPI strip shows the
* backlog count growing; Resume drains it in order.
*
* 4. Disconnect / reconnect. The simulator can drop the connection
* for a configurable interval. The status pill flips through
* open → reconnecting → open, and the gap in the event log
* stays visible so the operator knows what they missed.
*
* 5. Throughput control. Slider runs the stream from a calm 1
* event / sec up to a 50 event / sec firehose - shows the grid
* stays smooth at the high end.
*
* Editable columns (Priority, Notes) live entirely client-side; the
* stream never overwrites them, so there's no merge conflict to
* resolve at the cell level. Onboarding edits to the wire would be a
* call to the same `onCellValueChange` callback the demo already
* wires up.
*/
import {
SvGrid,
tableFeatures,
rowSortingFeature,
columnFilteringFeature,
renderSnippet,
type ColumnDef,
} from '@svgrid/grid'
import { createStreamSim, type StreamMessage } from '../shared/stream-sim'
import { createPrng } from '../shared/mock-api'
// ---- Domain ----------------------------------------------------------
type OrderStatus =
| 'received'
| 'confirmed'
| 'picking'
| 'packed'
| 'shipped'
| 'delivered'
| 'cancelled'
type OrderChannel = 'web' | 'mobile' | 'api' | 'phone' | 'partner'
type OrderPriority = 'low' | 'std' | 'high' | 'rush'
type OrderRegion = 'NA' | 'EMEA' | 'APAC' | 'LATAM'
type Order = {
id: string
customer: string
region: OrderRegion
channel: OrderChannel
items: number
amount: number
currency: 'USD' | 'EUR' | 'GBP'
status: OrderStatus
priority: OrderPriority
/** Promised delivery time as ms epoch. */
eta: number
notes: string
/** Monotonic per-row version stamped by the server on every event. */
rowVersion: number
/** ms epoch of the last server-side mutation for this order. */
lastChange: number
}
type StreamEvent =
| { type: 'order.created'; order: Order }
| { type: 'order.updated'; id: string; patch: Partial<Omit<Order, 'id'>>; rowVersion: number }
| { type: 'order.cancelled'; id: string; rowVersion: number }
// ---- Constants -------------------------------------------------------
const CHANNELS: readonly OrderChannel[] = ['web', 'mobile', 'api', 'phone', 'partner']
const STATUSES: readonly OrderStatus[] = [
'received', 'confirmed', 'picking', 'packed', 'shipped', 'delivered',
]
const REGIONS: readonly OrderRegion[] = ['NA', 'EMEA', 'APAC', 'LATAM']
const CURRENCIES: readonly Order['currency'][] = ['USD', 'EUR', 'GBP']
const PRIORITIES: readonly OrderPriority[] = ['low', 'std', 'high', 'rush']
const FIRST_NAMES = ['Alex', 'Jamie', 'Casey', 'Drew', 'Robin', 'Morgan', 'Riley', 'Quinn', 'Avery', 'Reese']
const LAST_NAMES = ['Park', 'Singh', 'Khan', 'Cohen', 'Nakamura', 'Silva', 'Diaz', 'Mehta', 'Olsen', 'Tran']
const STATUS_PROGRESSION: Record<OrderStatus, OrderStatus | null> = {
received: 'confirmed',
confirmed: 'picking',
picking: 'packed',
packed: 'shipped',
shipped: 'delivered',
delivered: null,
cancelled: null,
}
// ---- Synthetic event generator --------------------------------------
/**
* State the generator needs: existing order ids (so updates / cancels
* can target real rows) and a monotonic ID counter.
*/
const liveIds = new Set<string>()
let idCounter = 100000
const prng = createPrng(0x5EEDDEAD)
function pickFromSet<T>(s: Set<T>): T | null {
if (s.size === 0) return null
const idx = Math.floor(Math.random() * s.size)
let i = 0
for (const v of s) {
if (i === idx) return v
i += 1
}
return null
}
function newOrder(): Order {
const id = `ORD-${(idCounter++).toString(36).toUpperCase()}`
const status: OrderStatus = prng.next() < 0.85 ? 'received' : 'confirmed'
const items = prng.int(1, 8)
const unitPrice = 10 + Math.round(prng.next() * 240)
return {
id,
customer: `${prng.pick(FIRST_NAMES)} ${prng.pick(LAST_NAMES)}`,
region: prng.pick(REGIONS),
channel: prng.pick(CHANNELS),
items,
amount: items * unitPrice,
currency: prng.pick(CURRENCIES),
status,
priority: prng.next() < 0.7 ? 'std' : prng.pick(PRIORITIES),
eta: Date.now() + prng.int(20, 240) * 60_000,
notes: '',
rowVersion: 1,
lastChange: Date.now(),
}
}
/**
* Per-tick event picker. Mostly nudges existing orders forward in
* their lifecycle; occasionally spawns a new one. The mix biases
* toward updates (which exercise the in-place merge path more than
* creates / cancels).
*/
function generateEvent(): StreamEvent {
const roll = Math.random()
if (liveIds.size < 20 || roll < 0.22) {
const order = newOrder()
liveIds.add(order.id)
return { type: 'order.created', order }
}
const targetId = pickFromSet(liveIds)
if (!targetId) {
const order = newOrder()
liveIds.add(order.id)
return { type: 'order.created', order }
}
if (roll > 0.97) {
liveIds.delete(targetId)
return { type: 'order.cancelled', id: targetId, rowVersion: 0 /* filled in on receive */ }
}
// Update: pick what changed. Status progression is most common.
const update: Partial<Omit<Order, 'id'>> = {}
if (Math.random() < 0.55) {
// Status advance - we'll resolve the actual transition on receive
// by reading the current row's status (so cancelled orders won't
// suddenly progress). The patch shape carries the intent.
update.status = '__advance__' as OrderStatus // marker, resolved on receive
}
if (Math.random() < 0.2) {
update.eta = Date.now() + Math.floor(Math.random() * 180) * 60_000
}
if (Math.random() < 0.08) {
const delta = Math.round((Math.random() - 0.4) * 80)
update.amount = delta // marker for "+delta", resolved on receive
}
return { type: 'order.updated', id: targetId, patch: update, rowVersion: 0 }
}
// ---- Reactive state --------------------------------------------------
const features = tableFeatures({ rowSortingFeature, columnFilteringFeature })
// The grid's `data` prop expects an array. We store orders as an
// ordered list with newest at the top, plus a side index so deltas
// are O(1) lookups.
let orderList = $state.raw<Order[]>([])
const indexById = new Map<string, number>()
/** Cell-level flash pulses, keyed by `${id}:${field}`. Wiped each tick. */
let pulses = $state.raw<Record<string, 'up' | 'down' | 'neutral'>>({})
/** Event log shown on the side panel. Most recent first, capped. */
type LogEntry = {
kind: 'event' | 'status'
label: string
detail: string
ts: number
tone: 'ok' | 'warn' | 'info'
}
let eventLog = $state.raw<LogEntry[]>([])
// Stream controls
let rate = $state(8)
let connectionStatus = $state<'connecting' | 'open' | 'paused' | 'closed' | 'reconnecting'>('closed')
// ---- Initial backlog -------------------------------------------------
function seedInitial(count: number) {
const seed: Order[] = []
for (let i = 0; i < count; i += 1) {
const order = newOrder()
// Walk a random number of statuses forward so the backlog is
// visually varied (some packed, some shipped, etc.)
const walks = prng.int(0, 5)
let s: OrderStatus = order.status
for (let w = 0; w < walks; w += 1) {
const next = STATUS_PROGRESSION[s]
if (!next) break
s = next
}
order.status = s
liveIds.add(order.id)
seed.push(order)
}
seed.reverse()
orderList = seed
indexById.clear()
for (let i = 0; i < seed.length; i += 1) indexById.set(seed[i]!.id, i)
}
// ---- Stream subscription ---------------------------------------------
// svelte-ignore state_referenced_locally
const stream = createStreamSim<StreamEvent>({
generate: generateEvent,
rate,
jitter: 0.45,
})
let serverSeq = $state(0)
function applyEvent(event: StreamEvent): void {
const nextList = orderList.slice()
const nextPulses: Record<string, 'up' | 'down' | 'neutral'> = {}
if (event.type === 'order.created') {
const order = { ...event.order, rowVersion: ++serverSeq }
// Avoid duplicates if a flaky generator spits the same id (it
// shouldn't, but belt + braces).
if (indexById.has(order.id)) return
nextList.unshift(order)
// Insert at the top → every existing row's index shifts by 1.
indexById.clear()
for (let i = 0; i < nextList.length; i += 1) indexById.set(nextList[i]!.id, i)
nextPulses[`${order.id}:_row`] = 'up'
logEvent('event', `+ ${order.id}`, `${order.customer} · ${order.channel} · ${fmtMoney(order.amount, order.currency)}`, 'ok')
} else if (event.type === 'order.updated') {
const idx = indexById.get(event.id)
if (idx === undefined) return
const current = nextList[idx]!
// Out-of-order guard: ignore stale events.
const incomingVersion = event.rowVersion || ++serverSeq
if (incomingVersion <= current.rowVersion) return
const patch = event.patch
const updated: Order = { ...current, rowVersion: incomingVersion, lastChange: Date.now() }
if (patch.status === ('__advance__' as OrderStatus)) {
const next = STATUS_PROGRESSION[current.status]
if (!next) return // already at terminal state
updated.status = next
nextPulses[`${current.id}:status`] = 'neutral'
}
if (typeof patch.eta === 'number') {
updated.eta = patch.eta
nextPulses[`${current.id}:eta`] = patch.eta > current.eta ? 'down' : 'up'
}
if (typeof patch.amount === 'number') {
// We encoded amount as a DELTA in generateEvent.
const next = Math.max(0, current.amount + patch.amount)
nextPulses[`${current.id}:amount`] = next >= current.amount ? 'up' : 'down'
updated.amount = next
}
nextList[idx] = updated
logEvent('event', `~ ${current.id}`, summarisePatch(updated, current), 'info')
} else if (event.type === 'order.cancelled') {
const idx = indexById.get(event.id)
if (idx === undefined) return
const current = nextList[idx]!
const updated: Order = {
...current,
status: 'cancelled',
rowVersion: event.rowVersion || ++serverSeq,
lastChange: Date.now(),
}
nextList[idx] = updated
nextPulses[`${current.id}:_row`] = 'down'
// Schedule a removal in 2s so the operator sees the cancellation
// and then the row drops out of the list.
setTimeout(() => removeOrder(current.id), 2000)
logEvent('event', `× ${current.id}`, 'cancelled', 'warn')
}
orderList = nextList
pulses = nextPulses
}
function removeOrder(id: string): void {
const idx = indexById.get(id)
if (idx === undefined) return
const next = orderList.slice()
next.splice(idx, 1)
indexById.clear()
for (let i = 0; i < next.length; i += 1) indexById.set(next[i]!.id, i)
orderList = next
}
function logEvent(kind: 'event' | 'status', label: string, detail: string, tone: LogEntry['tone']) {
eventLog = [
{ kind, label, detail, ts: Date.now(), tone },
...eventLog,
].slice(0, 24)
}
// ---- Mount: seed + subscribe + start ---------------------------------
$effect(() => {
seedInitial(60)
const unsubscribe = stream.subscribe(handleMessage)
stream.start()
return () => {
unsubscribe()
stream.stop()
}
})
function handleMessage(msg: StreamMessage<StreamEvent>): void {
if (msg.kind === 'status') {
connectionStatus = msg.status
const tone = msg.status === 'open' ? 'ok' : msg.status === 'reconnecting' ? 'warn' : 'info'
logEvent('status', `state · ${msg.status}`, '', tone)
} else {
applyEvent(msg.data)
}
}
// ---- Editable cell flow ----------------------------------------------
function onCellValueChange(args: { rowIndex: number; columnId: string; newValue: unknown }): void {
const order = orderList[args.rowIndex]
if (!order) return
if (args.columnId !== 'priority' && args.columnId !== 'notes') return
const updated: Order = { ...order }
if (args.columnId === 'priority') {
const v = String(args.newValue) as OrderPriority
if (!PRIORITIES.includes(v)) return
updated.priority = v
} else {
updated.notes = String(args.newValue ?? '')
}
const next = orderList.slice()
next[args.rowIndex] = updated
orderList = next
}
// ---- Toolbar handlers -------------------------------------------------
function togglePause(): void {
if (connectionStatus === 'paused') stream.resume()
else stream.pause()
}
function simulateDisconnect(): void {
stream.disconnect(4500)
}
function setRate(value: number): void {
rate = value
stream.setRate(value)
}
// ---- KPI derivations --------------------------------------------------
const activeCount = $derived(
orderList.filter((o) => o.status !== 'delivered' && o.status !== 'cancelled').length,
)
const rushCount = $derived(
orderList.filter((o) => o.priority === 'rush' && o.status !== 'delivered' && o.status !== 'cancelled').length,
)
// ---- Formatters -------------------------------------------------------
function fmtMoney(amount: number, currency: string): string {
return amount.toLocaleString('en-US', { style: 'currency', currency, maximumFractionDigits: 0 })
}
function fmtEta(ts: number): string {
const ms = ts - Date.now()
if (ms <= 0) return 'now'
const minutes = Math.floor(ms / 60_000)
if (minutes < 60) return `in ${minutes}m`
const hours = Math.floor(minutes / 60)
const rest = minutes - hours * 60
return rest === 0 ? `in ${hours}h` : `in ${hours}h ${rest}m`
}
function fmtAgo(ts: number): string {
const ms = Date.now() - ts
if (ms < 1000) return 'now'
const s = Math.floor(ms / 1000)
if (s < 60) return `${s}s ago`
return `${Math.floor(s / 60)}m ago`
}
function fmtClock(ts: number): string {
return new Date(ts).toLocaleTimeString('en-US', { hour: '2-digit', minute: '2-digit', second: '2-digit', hour12: false })
}
function summarisePatch(updated: Order, prev: Order): string {
const parts: string[] = []
if (updated.status !== prev.status) parts.push(`status ${prev.status} → ${updated.status}`)
if (updated.amount !== prev.amount) parts.push(`amount ${prev.amount} → ${updated.amount}`)
if (updated.eta !== prev.eta) parts.push('eta shift')
return parts.length ? parts.join(' · ') : 'no-op'
}
function pulseClass(id: string, field: string): string {
const dir = pulses[`${id}:${field}`]
return dir === 'up' ? 'rt-pulse-up' : dir === 'down' ? 'rt-pulse-down' : dir === 'neutral' ? 'rt-pulse-neutral' : ''
}
function rowPulseClass(id: string): string {
return pulseClass(id, '_row')
}
</script>
<!-- ───────────────────── CELL SNIPPETS ───────────────────── -->
{#snippet IdCell(props: { row: Order })}
<span class={`mono rt-tick ${rowPulseClass(props.row.id)}`}>{props.row.id}</span>
{/snippet}
{#snippet CustomerCell(props: { row: Order })}
<span class="rt-cust">
<span class="rt-cust-name">{props.row.customer}</span>
<span class={`rt-region rt-region-${props.row.region}`}>{props.row.region}</span>
</span>
{/snippet}
{#snippet ChannelCell(props: { row: Order })}
<span class={`rt-channel rt-channel-${props.row.channel}`}>{props.row.channel}</span>
{/snippet}
{#snippet AmountCell(props: { row: Order })}
<span class={`rt-tick rt-amount ${pulseClass(props.row.id, 'amount')}`}>
{fmtMoney(props.row.amount, props.row.currency)}
</span>
{/snippet}
{#snippet StatusCell(props: { row: Order })}
<span class={`rt-tick status-pill status-${props.row.status} ${pulseClass(props.row.id, 'status')}`}>
<span class="status-dot"></span>{props.row.status}
</span>
{/snippet}
{#snippet PriorityCell(props: { row: Order })}
<span class={`rt-priority rt-priority-${props.row.priority}`}>{props.row.priority}</span>
{/snippet}
{#snippet EtaCell(props: { row: Order })}
{@const overdue = props.row.eta < Date.now()}
<span class={`rt-tick rt-eta ${overdue ? 'rt-eta-overdue' : ''} ${pulseClass(props.row.id, 'eta')}`}>
{fmtEta(props.row.eta)}
</span>
{/snippet}
{#snippet UpdatedCell(props: { row: Order })}
<span class="rt-ago">{fmtAgo(props.row.lastChange)}</span>
{/snippet}
<!-- ───────────────────── LAYOUT ───────────────────── -->
<section class="rt-shell flex flex-col flex-1 min-h-0 gap-3">
<!-- KPI strip -->
<div class="rt-kpi-strip">
<div class="rt-kpi">
<div class="rt-kpi-label">Connection</div>
<div class={`rt-kpi-value tabular-nums rt-status-${connectionStatus}`}>
{connectionStatus.toUpperCase()}
</div>
<div class="rt-kpi-foot">
<span class={connectionStatus === 'open' ? 'rt-dot rt-dot-live' : connectionStatus === 'reconnecting' ? 'rt-dot rt-dot-warn' : 'rt-dot'}></span>
{stream.stats.reconnects} reconnects
</div>
</div>
<div class="rt-kpi">
<div class="rt-kpi-label">Active orders</div>
<div class="rt-kpi-value tabular-nums">{activeCount.toLocaleString()}</div>
<div class="rt-kpi-foot">{rushCount} rush · {orderList.length} on screen</div>
</div>
<div class="rt-kpi">
<div class="rt-kpi-label">Events</div>
<div class="rt-kpi-value tabular-nums">{stream.stats.emitted.toLocaleString()}</div>
<div class="rt-kpi-foot">{rate}/sec · seq #{serverSeq}</div>
</div>
<div class="rt-kpi">
<div class="rt-kpi-label">Backlog</div>
<div class={`rt-kpi-value tabular-nums ${stream.stats.buffered > 0 ? 'rt-down' : ''}`}>
{stream.stats.buffered.toLocaleString()}
</div>
<div class="rt-kpi-foot">{connectionStatus === 'paused' ? 'paused' : 'flowing'}</div>
</div>
<div class="rt-kpi">
<div class="rt-kpi-label">Wire lag</div>
<div class="rt-kpi-value tabular-nums">{stream.stats.avgLagMs} ms</div>
<div class="rt-kpi-foot">last {stream.stats.lastLagMs} ms</div>
</div>
</div>
<!-- Toolbar -->
<div class="rt-toolbar">
<button
type="button"
class="rt-btn rt-btn-primary"
onclick={togglePause}
>{connectionStatus === 'paused' ? '▶ Resume' : '⏸ Pause stream'}</button>
<button
type="button"
class="rt-btn"
onclick={simulateDisconnect}
>⚡ Simulate disconnect</button>
<label class="rt-throttle">
<span class="rt-throttle-label">Throughput</span>
<input
type="range"
min="1"
max="50"
step="1"
bind:value={rate}
oninput={(event) => setRate(Number((event.currentTarget as HTMLInputElement).value))}
/>
<span class="rt-throttle-value tabular-nums">{rate}/s</span>
</label>
<div class="rt-toolbar-spacer"></div>
<span class="rt-hint">
Editable: <strong>Priority</strong> · <strong>Notes</strong>
</span>
</div>
<!-- Main: grid + event log -->
<div class="rt-body">
<div class="rt-grid-wrap">
<SvGrid responsive={true}
columnResize
data={orderList}
columns={[
{
field: 'id', header: 'Order', width: 140, editable: false,
cell: (ctx) => renderSnippet(IdCell, { row: ctx.row.original }),
},
{
field: 'customer', header: 'Customer', width: 200, editable: false,
cell: (ctx) => renderSnippet(CustomerCell, { row: ctx.row.original }),
},
{
field: 'channel', header: 'Channel', width: 110, editable: false,
cell: (ctx) => renderSnippet(ChannelCell, { row: ctx.row.original }),
},
{
field: 'items', header: 'Items', editorType: 'number', width: 80, editable: false,
},
{
field: 'amount', header: 'Amount', editorType: 'number', width: 130, editable: false,
cell: (ctx) => renderSnippet(AmountCell, { row: ctx.row.original }),
},
{
field: 'status', header: 'Status', width: 130, editable: false,
cell: (ctx) => renderSnippet(StatusCell, { row: ctx.row.original }),
},
{
field: 'priority', header: 'Priority', width: 110,
editorType: 'list',
editorOptions: PRIORITIES as unknown as ReadonlyArray<string>,
cell: (ctx) => renderSnippet(PriorityCell, { row: ctx.row.original }),
},
{
field: 'eta', header: 'ETA', editorType: 'number', width: 120, editable: false,
cell: (ctx) => renderSnippet(EtaCell, { row: ctx.row.original }),
},
{
field: 'lastChange', header: 'Updated', editorType: 'number', width: 100, editable: false,
cell: (ctx) => renderSnippet(UpdatedCell, { row: ctx.row.original }),
},
{
field: 'notes', header: 'Notes', width: 200, editorType: 'text',
},
] satisfies ColumnDef<typeof features, Order>[]}
features={features}
filterMode="menu"
selectionMode="cell"
enableInlineEditing={true}
enableCellSelection={true}
rowHeight={36}
containerHeight="100%"
fitColumns={false}
onCellValueChange={onCellValueChange}
/>
</div>
<aside class="rt-log">
<header class="rt-log-head">
<span>Event log</span>
<span class="rt-log-stats tabular-nums">{eventLog.length}</span>
</header>
<div class="rt-log-list">
{#each eventLog as entry (entry.ts)}
<div class={`rt-log-row rt-log-${entry.tone}`}>
<span class="rt-log-clock mono">{fmtClock(entry.ts)}</span>
<span class="rt-log-label">{entry.label}</span>
{#if entry.detail}
<span class="rt-log-detail">{entry.detail}</span>
{/if}
</div>
{:else}
<div class="rt-log-empty">Stream idle</div>
{/each}
</div>
</aside>
</div>
</section>
<style>
/* ─── KPI strip ──────────────────────────────────────────────── */
.rt-kpi-strip {
display: grid;
grid-template-columns: repeat(5, minmax(0, 1fr));
gap: 10px;
flex-shrink: 0;
}
.rt-kpi {
border: 1px solid var(--sg-border, #e2e8f0);
background: var(--sg-bg, #ffffff);
border-radius: 10px;
padding: 12px 14px;
}
.rt-kpi-label {
font-size: 11px;
text-transform: uppercase;
letter-spacing: 0.06em;
color: var(--sg-muted, #64748b);
margin-bottom: 6px;
}
.rt-kpi-value {
font-size: 22px;
font-weight: 700;
line-height: 1.1;
letter-spacing: -0.01em;
}
.rt-kpi-foot {
margin-top: 6px;
font-size: 11px;
color: var(--sg-muted, #64748b);
display: flex; align-items: center; gap: 6px;
}
.rt-status-open { color: #16a34a; }
.rt-status-paused { color: #ca8a04; }
.rt-status-reconnecting { color: #d97706; }
.rt-status-connecting { color: #2563eb; }
.rt-status-closed { color: var(--sg-muted, #64748b); }
:global([data-theme='dark']) .rt-status-open { color: #4ade80; }
:global([data-theme='dark']) .rt-status-paused { color: #fbbf24; }
:global([data-theme='dark']) .rt-status-reconnecting { color: #fb923c; }
:global([data-theme='dark']) .rt-status-connecting { color: #60a5fa; }
.rt-dot {
display: inline-block; width: 7px; height: 7px; border-radius: 50%;
background: var(--sg-muted, #94a3b8);
}
.rt-dot-live {
background: #16a34a;
animation: rt-dot-live 1.4s ease-out infinite;
}
.rt-dot-warn {
background: #d97706;
animation: rt-dot-live 0.8s ease-out infinite;
}
@keyframes rt-dot-live {
0% { box-shadow: 0 0 0 0 rgba(22,163,74,0.5); }
70% { box-shadow: 0 0 0 7px rgba(22,163,74,0); }
100% { box-shadow: 0 0 0 0 rgba(22,163,74,0); }
}
.rt-up { color: #16a34a; }
.rt-down { color: #dc2626; }
:global([data-theme='dark']) .rt-up { color: #4ade80; }
:global([data-theme='dark']) .rt-down { color: #f87171; }
/* ─── Toolbar ────────────────────────────────────────────────── */
.rt-toolbar {
display: flex;
flex-wrap: wrap;
align-items: center;
gap: 10px;
flex-shrink: 0;
}
.rt-toolbar-spacer { flex: 1 1 auto; }
.rt-btn {
border: 1px solid var(--sg-border, #cbd5e1);
background: var(--sg-bg, #ffffff);
color: var(--sg-fg, #1e293b);
border-radius: 6px;
padding: 5px 12px;
font-size: 12px;
cursor: pointer;
}
.rt-btn:hover { background: var(--sg-header-bg, #f1f5f9); }
.rt-btn-primary {
border-color: transparent;
background: var(--sg-accent, #2563eb);
color: var(--sg-on-accent, #fff);
}
.rt-btn-primary:hover { filter: brightness(1.05); }
.rt-throttle {
display: inline-flex;
align-items: center;
gap: 8px;
padding: 4px 10px;
border: 1px solid var(--sg-border, #cbd5e1);
border-radius: 6px;
background: var(--sg-bg, #ffffff);
font-size: 11.5px;
color: var(--sg-muted, #64748b);
}
.rt-throttle input[type='range'] { width: 140px; }
.rt-throttle-value { color: var(--sg-fg, #1e293b); font-weight: 600; min-width: 38px; }
.rt-hint {
font-size: 11.5px;
color: var(--sg-muted, #64748b);
}
.rt-hint strong {
color: var(--sg-fg, #1e293b);
font-weight: 600;
}
/* ─── Body grid + log ────────────────────────────────────────── */
.rt-body {
flex: 1 1 auto;
min-height: 0;
display: grid;
grid-template-columns: minmax(0, 1fr) 300px;
gap: 10px;
}
.rt-grid-wrap { min-width: 0; }
/* ─── Cell badges ─────────────────────────────────────────────── */
:global(.mono) {
font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
font-size: 12px;
letter-spacing: 0.02em;
}
:global(.rt-tick) {
display: inline-flex;
align-items: center;
gap: 4px;
padding: 0 3px;
border-radius: 3px;
font-variant-numeric: tabular-nums;
}
:global(.rt-amount) { font-weight: 600; }
:global(.rt-pulse-up) { animation: rt-pulse-up 600ms ease-out; }
:global(.rt-pulse-down) { animation: rt-pulse-down 600ms ease-out; }
:global(.rt-pulse-neutral) { animation: rt-pulse-neutral 600ms ease-out; }
@keyframes rt-pulse-up { 0% { background: rgba(34,197,94,0.55); } 100% { background: transparent; } }
@keyframes rt-pulse-down { 0% { background: rgba(239,68,68,0.55); } 100% { background: transparent; } }
@keyframes rt-pulse-neutral { 0% { background: rgba(59,130,246,0.55); } 100% { background: transparent; } }
:global(.rt-cust) {
display: inline-flex;
align-items: center;
gap: 6px;
}
:global(.rt-cust-name) { font-weight: 500; }
:global(.rt-region) {
display: inline-block;
padding: 1px 6px;
font-size: 10px;
font-weight: 700;
border-radius: 4px;
letter-spacing: 0.05em;
}
:global(.rt-region-NA) { background: #dbeafe; color: #1d4ed8; }
:global(.rt-region-EMEA) { background: #fce7f3; color: #9d174d; }
:global(.rt-region-APAC) { background: #ccfbf1; color: #115e59; }
:global(.rt-region-LATAM) { background: #ffedd5; color: #9a3412; }
:global([data-theme='dark'] .rt-region-NA) { background: rgba(59,130,246,.18); color: #93c5fd; }
:global([data-theme='dark'] .rt-region-EMEA) { background: rgba(236,72,153,.18); color: #f9a8d4; }
:global([data-theme='dark'] .rt-region-APAC) { background: rgba(20,184,166,.18); color: #5eead4; }
:global([data-theme='dark'] .rt-region-LATAM) { background: rgba(249,115,22,.18); color: #fdba74; }
:global(.rt-channel) {
font-family: ui-monospace, SFMono-Regular, Menlo, monospace;
font-size: 11px;
text-transform: uppercase;
letter-spacing: 0.05em;
padding: 2px 7px;
border-radius: 4px;
background: var(--sg-header-bg, #f1f5f9);
color: var(--sg-fg, #1e293b);
}
:global(.status-pill) {
display: inline-flex;
align-items: center;
gap: 5px;
padding: 2px 9px;
border-radius: 999px;
font-size: 11px;
font-weight: 600;
text-transform: capitalize;
}
:global(.status-dot) {
display: inline-block;
width: 6px; height: 6px; border-radius: 50%;
background: currentColor;
}
:global(.status-received) { background: #dbeafe; color: #1d4ed8; }
:global(.status-confirmed) { background: #e0e7ff; color: #3730a3; }
:global(.status-picking) { background: #fef3c7; color: #92400e; }
:global(.status-packed) { background: #fde68a; color: #78350f; }
:global(.status-shipped) { background: #ccfbf1; color: #115e59; }
:global(.status-delivered) { background: #dcfce7; color: #166534; }
:global(.status-cancelled) { background: #fee2e2; color: #b91c1c; }
:global([data-theme='dark'] .status-received) { background: rgba(59,130,246,.18); color: #93c5fd; }
:global([data-theme='dark'] .status-confirmed) { background: rgba(99,102,241,.18); color: #a5b4fc; }
:global([data-theme='dark'] .status-picking) { background: rgba(245,158,11,.18); color: #fbbf24; }
:global([data-theme='dark'] .status-packed) { background: rgba(217,119,6,.18); color: #fcd34d; }
:global([data-theme='dark'] .status-shipped) { background: rgba(20,184,166,.18); color: #5eead4; }
:global([data-theme='dark'] .status-delivered) { background: rgba(34,197,94,.18); color: #4ade80; }
:global([data-theme='dark'] .status-cancelled) { background: rgba(239,68,68,.18); color: #f87171; }
:global(.rt-priority) {
display: inline-block;
padding: 1px 8px;
font-size: 11px;
font-weight: 600;
border-radius: 4px;
text-transform: uppercase;
letter-spacing: 0.05em;
}
:global(.rt-priority-low) { background: #e2e8f0; color: #334155; }
:global(.rt-priority-std) { background: #dbeafe; color: #1d4ed8; }
:global(.rt-priority-high) { background: #fef3c7; color: #92400e; }
:global(.rt-priority-rush) { background: #fee2e2; color: #b91c1c; }
:global([data-theme='dark'] .rt-priority-low) { background: rgba(148,163,184,.2); color: #cbd5e1; }
:global([data-theme='dark'] .rt-priority-std) { background: rgba(59,130,246,.18); color: #93c5fd; }
:global([data-theme='dark'] .rt-priority-high) { background: rgba(245,158,11,.18); color: #fbbf24; }
:global([data-theme='dark'] .rt-priority-rush) { background: rgba(239,68,68,.18); color: #f87171; }
:global(.rt-eta) { color: var(--sg-fg, #1e293b); }
:global(.rt-eta-overdue) { color: #dc2626; font-weight: 600; }
:global([data-theme='dark'] .rt-eta-overdue) { color: #f87171; }
:global(.rt-ago) {
font-size: 11px;
color: var(--sg-muted, #64748b);
font-variant-numeric: tabular-nums;
}
/* ─── Event log panel ─────────────────────────────────────────── */
.rt-log {
border: 1px solid var(--sg-border, #e2e8f0);
background: var(--sg-bg, #ffffff);
border-radius: 10px;
display: flex;
flex-direction: column;
overflow: hidden;
min-height: 0;
}
.rt-log-head {
display: flex;
align-items: center;
justify-content: space-between;
padding: 10px 12px;
border-bottom: 1px solid var(--sg-border, #e2e8f0);
background: var(--sg-header-bg, #f1f5f9);
font-size: 11.5px;
font-weight: 600;
text-transform: uppercase;
letter-spacing: 0.06em;
}
.rt-log-stats { color: var(--sg-muted, #64748b); font-weight: 500; }
.rt-log-list {
flex: 1 1 auto;
overflow: auto;
padding: 6px 0;
}
.rt-log-row {
display: grid;
grid-template-columns: 64px 100px 1fr;
gap: 6px;
align-items: baseline;
padding: 4px 12px;
font-size: 11.5px;
border-left: 2px solid transparent;
}
.rt-log-ok { border-left-color: #16a34a; }
.rt-log-warn { border-left-color: #ca8a04; }
.rt-log-info { border-left-color: #2563eb; }
.rt-log-clock { color: var(--sg-muted, #64748b); font-size: 10.5px; }
.rt-log-label { font-weight: 600; }
.rt-log-detail { color: var(--sg-muted, #64748b); }
.rt-log-empty {
padding: 16px;
text-align: center;
color: var(--sg-muted, #64748b);
font-style: italic;
font-size: 11.5px;
}
/* Phone: same shape - content-sized rows, and the order log scrolls inside its card. */
@media (max-width: 639px), (max-height: 500px) and (pointer: coarse) {
.rt-body { grid-auto-rows: max-content; }
.rt-log-list { max-height: 45vh; overflow-y: auto; }
}
</style>More Real-time & Streaming examples
- Stock market - live - WebSocket-style ticking feed. Cells flash on up/down ticks, pause control, throttle.
- Industrial - IoT sensors - Live sensor floor: threshold-driven status, sparkline trends, group by line.
- Industrial dashboard - KPI cards plus live line-status and active-alarms grids, on a 2-second tick.
- Real-time collaboration - Presence (who is here + where their cursor is) and live edits (a change in one client lands in every other) over a pluggable transport. createCollaboration + broadcastChannelTransport sync cursors and edits across tabs with zero backend; swap the transport for a WebSocket to go cross-machine. Also the substrate for multiple AI agents editing one grid.
- Transaction API (batched) - api.applyTransaction({ add, update, remove }) applies a batch of row mutations in ONE data update - the high-frequency streaming path. update and remove-by-id match on getRowId; remove also accepts row refs. Live order book ticking via batched transactions.