# State and events

Read builds, react to changes, and clean up a mounted calculator.

Source: https://warcraftforever.com/developers/talents/lifecycle/

`ready` resolves with the initial state. Use `getState()`, `setBuild({ code, revision })`, `update(options)`, `on(event, listener)`, and `destroy()` for later changes. `on()` returns an unsubscribe function. Updates resolve with committed state; an invalid build or revision rejects and leaves the previous state intact.

State includes the class, code, revision, full allocation, points spent and remaining, maximum level, completion, and standalone share URL. `complete` means a valid build has spent exactly `maxLevel − 9` points. Listen for `ready`, `change`, `complete`, `submit`, or `error`. Save appears only when an editable build is complete; clicking it emits `submit`. `change` and the transition to `complete` describe user edits. API updates return state without emitting these edit events. Error listeners receive an Error object.

`state.code` remains the deprecated compact format for existing integrations. Call `exportBuild('blizzard')` for an in-game string or `exportBuild('structured')` for selected trees and spells. See [build exports](https://warcraftforever.com/developers/talents/exports/) for the formats and revision requirements.

Mount after the target element and script exist. Multiple mounts are independent. Await an update before depending on it; a newer update or destroy rejects an unfinished update with `AbortError`. Updates preserve the current build unless you supply `build`; pass `build: undefined` to reset. Changing class without a new build resets its build and tree selection. Destroy on host component unmount. These scripts do not require React on your site.