# State properties These are returned in an object by `useAsync()` or provided by `` as render props to the `children` function: * [`data`](/api/state.md#data) Last resolved promise value, maintained when new error arrives. * [`error`](/api/state.md#error) Rejected promise reason, cleared when new data arrives. * [`value`](/api/state.md#value) The value of `data` or `error`, whichever was last updated. * [`initialValue`](/api/state.md#initialvalue) The data or error that was provided through the `initialValue` prop. * [`startedAt`](/api/state.md#startedat) When the current/last promise was started. * [`finishedAt`](/api/state.md#finishedat) When the last promise was fulfilled or rejected. * [`status`](/api/state.md#status) One of: `initial`, `pending`, `fulfilled`, `rejected`. * [`isInitial`](/api/state.md#isinitial) true when no promise has ever started, or one started but was cancelled. * [`isPending`](/api/state.md#ispending) true when a promise is currently awaiting settlement. Alias: `isLoading` * [`isFulfilled`](/api/state.md#isfulfilled) true when the last promise was fulfilled. Alias: `isResolved` * [`isRejected`](/api/state.md#isrejected) true when the last promise was rejected. * [`isSettled`](/api/state.md#issettled) true when the last promise was fulfilled or rejected (not initial or pending). * [`counter`](/api/state.md#counter) The number of times a promise was started. * [`promise`](/api/state.md#promise) A reference to the internal wrapper promise, which can be chained on. * [`run`](/api/state.md#run) Invokes the `deferFn`. * [`reload`](/api/state.md#reload) Re-runs the promise when invoked, using any previous arguments. * [`cancel`](/api/state.md#cancel) Cancel any pending promise. * [`setData`](/api/state.md#setdata) Sets `data` to the passed value, unsets `error` and cancels any pending promise. * [`setError`](/api/state.md#seterror) Sets `error` to the passed value and cancels any pending promise. ## `data` > `any` Last resolved promise value, maintained when new error arrives. ## `error` > `Error` Rejected promise reason, cleared when new data arrives. ## `value` > `any | Error` The data or error that was last provided (either through `initialValue` or by settling a promise). ## `initialValue` > `any | Error` The data or error that was originally provided through the `initialValue` prop. ## `startedAt` > `Date` Tracks when the current/last promise was started. ## `finishedAt` > `Date` Tracks when the last promise was resolved or rejected. ## `status` > `string` One of: `initial`, `pending`, `fulfilled`, `rejected`. These are available for import as `statusTypes`. ## `isInitial` > `boolean` `true` while no promise has started yet, or one was started but cancelled. ## `isPending` > `boolean` `true` while a promise is pending (loading), `false` otherwise. Alias: `isLoading` ## `isFulfilled` > `boolean` `true` when the last promise was fulfilled (resolved to a value). Alias: `isResolved` ## `isRejected` > `boolean` `true` when the last promise was rejected. ## `isSettled` > `boolean` `true` when the last promise was either fulfilled or rejected (i.e. not initial or pending) ## `counter` > `number` The number of times a promise was started. ## `promise` > `Promise` A reference to the internal wrapper promise created when starting a new promise (either automatically or by invoking `run` / `reload`). It fulfills or rejects along with the provided `promise` / `promiseFn` / `deferFn`. Useful as a chainable alternative to the `onResolve` / `onReject` callbacks. Warning! If you chain on `promise`, you MUST provide a rejection handler (e.g. `.catch(...)`). Otherwise React will throw an exception and crash if the promise rejects. ## `run` > `function(...args: any[]): void` Runs the `deferFn`, passing any arguments provided as an array. When used with `useFetch`, `run` has several overloaded signatures: > `function(override: OverrideParams | (params: OverrideParams) => OverrideParams): void` > > `function(event: SyntheticEvent | Event): void` > > `function(): void` Where `type OverrideParams = { resource?: RequestInfo } & Partial`. This way you can run the `fetch` request with custom `resource` and `init`. If `override` is an object it will be spread over the default `resource` and `init` for `fetch`. If it's a function it will be invoked with the params defined with `useFetch`, and should return an `override` object. This way you can either extend or override the value of `resource` and `init`, for example to change the URL or set custom request headers. ## `reload` > `function(): void` Re-runs the promise when invoked, using the previous arguments. ## `cancel` > `function(): void` Cancels the currently pending promise by ignoring its result and calls `abort()` on the AbortController. ## `setData` > `function(data: any, callback?: () => void): any` Function that sets `data` to the passed value, unsets `error` and cancels any pending promise. Takes an optional callback which is invoked after the state update is completed. Returns the data to enable chaining. ## `setError` > `function(error: Error, callback?: () => void): Error` Function that sets `error` to the passed value and cancels any pending promise. Takes an optional callback which is invoked after the state update is completed. 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