peek

Extract raw values from MaybeObservable types without registering a reactive dependency (works with both raw values and Legend-State observables).

Use peek when you need to read a value once (e.g. at mount time) and do not want the caller to re-run when the observable changes. Use get inside reactive contexts (useObserve, useObservable) when reactivity is needed.

Usage

import { peek } from "@usels/web";
import { observable } from "@legendapp/state";

// With raw values — returned as-is
const rawValue = { name: "John", age: 30 };
console.log(peek(rawValue)); // { name: 'John', age: 30 }
console.log(peek(rawValue, "name")); // 'John'

// With observables — reads without tracking
const obs$ = observable({ name: "John", age: 30 });
console.log(peek(obs$)); // { name: 'John', age: 30 }  — no dep registered
console.log(peek(obs$, "name")); // 'John'                     — no dep registered

Type Declarations

export declare function peek<T>(maybeObservable: MaybeObservable<T>): T;
export declare function peek<T>(maybeObservable: MaybeObservable<T> | undefined): T | undefined;
export declare function peek<T, K extends keyof T>(
  maybeObservable: MaybeObservable<T>,
  key: K
): T[K] | undefined;

Type Declarations

export declare function peek<T>(maybeObservable: MaybeObservable<T>): T;
export declare function peek<T>(maybeObservable: MaybeObservable<T> | undefined): T | undefined;
export declare function peek<T, K extends keyof T>(maybeObservable: MaybeObservable<T>, key: K): T[K] | undefined;

Source

View on GitHub

Contributors

• tigerwest

Changelog

• a7392ab 2026-03-06 - feat(core,browser): add sync strategy hooks (tigerwest)