Reactivity

createOptimistic

Creates an optimistic signal that can be used to optimistically update a value and then revert it back to the previous value at end of transition.

When called with a plain value, creates an optimistic signal with SignalOptions (name, equals, ownedWrite, unobserved). When called with a function, creates a writable optimistic memo with SignalOptions & MemoOptions (adds id, lazy).

// Plain optimistic signal
const [state, setState] = createOptimistic<T>(value, options?: SignalOptions<T>);
// Writable optimistic memo (function overload)
const [state, setState] = createOptimistic<T>(fn, options?: SignalOptions<T> & MemoOptions<T>);

Import

import { createOptimistic } from "solid-js";

Type signature

function createOptimistic<T>(): Signal<T | undefined>;
function createOptimistic<T>(
  value: Exclude<T, Function>,
  options?: SignalOptions<T>
): Signal<T>;
function createOptimistic<T>(
  fn: ComputeFunction<T>,
  options?: SignalOptions<T> & MemoOptions<T>
): Signal<T>;

Parameters

`value`

Initial value of the signal; if empty, the signal's type will automatically extended with undefined

`options`

Optional object with a name for debugging purposes and equals, a comparator function for the previous and next value to allow fine-grained control over the reactivity

Return value

[state: Accessor<T>, setState: Setter<T>]

Examples

const [todos, setTodos] = createOptimistic(initialTodos);

const addTodo = action(function* (text: string) {
  const tempId = crypto.randomUUID();
  setTodos((t) => [...t, { id: tempId, text, pending: true }]); // optimistic
  const saved = yield api.createTodo(text);
  setTodos((t) => t.map((x) => (x.id === tempId ? saved : x))); // reconcile
});

Last updated: 7/4/26, 6:21 PMEdit this pageReport an issue with this page