FAQ

I see candles but my indicator doesn't show — what's wrong?

You almost certainly haven't registered a scripting engine. Vela™ ships none — a bare chart is candles, drawings and native indicators only. Install an engine and register it before (or any time before) you add an indicator:

import { PineEngine } from '@luxalgo/vela-pinets'; // npm i @luxalgo/vela-pinets pinets
chart.registerEngine('pine', new PineEngine());

Calling addIndicator for a language with no registered engine throws an actionable error rather than silently doing nothing. See Scripting engines and Quickstart.

Can I use Vela™ fully offline, with no API key?

Yes — pass your own bars via the data option. No network call, no key, nothing to configure:

new Vela('#chart', { data: myBars, timeframe: '1h' });

data and provider fetch are mutually exclusive. With offline data, timeframe is still used for bar spacing and axis labels; provider/symbol/bars are ignored. This is the recommended path for first runs, demos, and tests. See Examples.

How does live mode work?

Set live: true. On top of the loaded history, the chart subscribes to ticks: the forming (last) candle updates in place, and a new bar is appended when the interval rolls over. Indicators recompute as bars change, and you can observe ticks with chart.on('bar', …). The forming bar is never cached as closed history. With offline data, the live example synthesizes ticks locally — still no network.

How do I turn off caching?

The default feed (a multi-provider registry) caches closed bars in memory, so re-runs for the same symbol reuse bars and only re-fetch the tail. Caching is built into that feed and isn't separately toggleable. To bypass it entirely, inject your own bare MarketDataFeed through the deps swap point — a custom feed is used as-is, with no registry and no auto-cache:

new Vela('#chart', options, { dataFeed: myCustomFeed });

See Adding a data provider for the provider model and the feed contract, and Data providers for registering providers with chart.data.

Which renderer and which engine should I use?

Renderer: the native renderer is the default (WebGL2 with a canvas2d fallback) and the only bundled backend; a custom IChartRenderer class can replace it wholesale.

Engine: none is bundled — you install one. For Pine Script, the @luxalgo/vela-pinets addon exports two forms with identical semantics:

• In-process (PineEngine) — runs on the main thread; simplest setup.
• Web-Worker (PineWorkerEngine) — the same Pine, off the main thread, which keeps the UI responsive during heavy computation. It streams live exactly like the in-process form: a persistent session lives inside the worker, so each tick sends one bar across and the script updates incrementally.

Register whichever form you want under the pine language id — the call site is identical:

import { PineWorkerEngine } from '@luxalgo/vela-pinets';
chart.registerEngine('pine', new PineWorkerEngine());

Default to the worker form; reach for the in-process one when you want the simplest possible setup or a debugger stepping through engine code on the main thread. For any other language, write an engine against the port.

My drawings don't appear, or I can't edit them — why?

Interactive drawing needs a renderer that supports it. The native renderer does; the a minimal adapter may not. Check chart.drawings.supported — when it's false, the interactive methods warn and no-op (and the toolbar won't show), but chart.drawings.add(...), toJSON()/fromJSON(), and undo()/redo() still work, because the drawing model is core-owned.

Do my drawings persist across reloads?

Not automatically. Snapshot them with chart.drawings.toJSON(), store the document yourself (localStorage, your backend, …), and restore with chart.drawings.fromJSON(doc). Anchors are in time + price, so restored drawings land on the right bars regardless of the current zoom. See Drawing Tools.

How do I hide the toolbar but still script drawings?

Construct with drawings: false (or call chart.drawings.showToolbar(false)). The bar disappears, but the whole chart.drawings API keeps working headlessly.

Can I remove the in-chart Vela™ logo?

The bottom-left mark is Vela™'s attribution notice (see the repository's NOTICE file, per Apache-2.0 §4(d)). It renders by default on every chart. You may turn it off — chart.renderer.set('attribution', false) — only if you display an equivalent visible attribution ("Vela™" linking to the project page) elsewhere on the same page or screen. Removing the attribution entirely is not permitted by the license.

How stable is the API?

The API is still evolving and may change as the library develops. Expect occasional breaking changes, and pin to a known-good source revision when you need stability.