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derived() function
Returns a ReadonlyRef whose value will always point to the latest result of the given function. The function will only be executed once per set of values.
Signature:
export declare function derived<T>(fn: () => T): ReadonlyRef<T>;
Parameters
| Parameter | Type | Description |
|---|---|---|
| fn | () => T | A function which returns a derivation of tracked objects or references. |
Returns:
ReadonlyRef<T>
Example
const name = ref('Preact');
const greet = derived(() => `Hello ${name.current}!`);
console.log(greet.current); // => 'Hello Preact'
name.current = 'React';
console.log(greet.current); // => 'Hello React'