immutable

• immutable<T>(store: T | Readable<T> | Writable<T>, clone?: ICloner<T>, start?: IStoreStartStopNotifier<T>): Readable<T> | Writable<T>

• Returns a Readable / Writable Svelte Store, that clones the stored value before every I/O operation, to prevent untracked data mutations

  NOTE: If a non-Store value is passed as store, then it will be wrapped in a Writable Store

  NOTE: By default, immutable can ONLY shallow clone Objects and Arrays. If deep or specific cloning is needed, pass a clone function

  For a simple example, in making a Readable Store immutable:

  import {readable} from "svelte/store";
  import {immutable} from "svelte-commons/lib/stores/shared";
  
  const initial_value = {key: "value"};
  
  const readable_store = readable(initial_value);
  
  const store = immutable(readable_store);
  
  store.subscribe((value) => {
      console.log({initial_value, value});
      console.log(value === initial_value);
  }); // logs: `false`

  Another simple example, but this time making a Writable Store immutable:

  import {derived, writable} from "svelte/store";
  import {immutable} from "svelte-commons/lib/stores/shared";
  
  const initial_value = {key: "value"};
  
  const writable_store = writable(initial_value);
  
  const store = immutable(writable_store);
  
  // NOTE: A `derived` Store is used here for simpler looking code
  const derived_store = derived([writable_store, store], ([$writable, $store]) => {
      console.log({$writable, $store});
      console.log($writable === $store);
  });
  
  // NOTE: This subscription is just so the `derived` callback starts running
  derived_store.subscribe(() => {}); // logs: `false`
  
  store.set({key: "not a value!"}); // logs: `false`

  Type parameters

  • T

  Parameters

  • store: T | Readable<T> | Writable<T>

  • Default value clone: ICloner<T> = clone_value

  • Optional start: IStoreStartStopNotifier<T>

  Returns Readable<T> | Writable<T>