merged

• merged<T>(value: T, merger?: IMerger<T>, start?: IStoreStartStopNotifier<T>): Writable<T>

• Represents a Writable Svelte Store for a Store that performs shallow delta updates to the current object

  Without Custom "Merger"

  import {merged} from "svelte-commons/lib/stores/shared";
  
  // The Store is initialized with an empty base object, which is immutable by default
  const store = merged({});
  
  // Will log every change to the Store
  store.subscribe(console.log);
  
  store.set({first_name: "John", last_name: "Smith"}); // logs: `{first_name: "John", last_name: "Smith"}`
  store.set({first_name: "Jane"}); // logs: `{first_name: "Jane", last_name: "Smith"}`

  With Custom "Merger"

  import {merged} from "svelte-commons/lib/stores/shared";
  
  const initial_data = {
      name: "James Bond",
      job: {
          title: "Spy",
          agency: "MI6",
          country: "England"
      }
  };
  
  function merger(a, b) {
      // By default, the default "Merger" only merges the top-level object keys, and spreads
      // all of them. For more performance, and to target nested keys, we can use a custom function
      const { name: a_name, job: a_job = {} } = a;
      const { name: b_name, job: b_job = {} } = b;
  
      return {
          name: b_name || a_name,
          job: {
              title: b_job.title || a_job.title,
              agency: b_job.agency || a_job.agency,
              country: b_job.country || a_job.country
          }
      };
  }
  
  // The Store is initialized with an empty base object, which is immutable by default
  const store = merged(initial_data, merger);
  
  // Will log every change to the Store
  store.subscribe(console.log); // logs: `{name:"James Bond",job:{title:"Spy",agency:"MI6",country:"England"}}`
  
  store.set({job: {agency: "FBI", country: "USA"}}); // logs: `{name:"James Bond",job:{title:"Spy",agency:"FBI",country:"USA"}}`

  Type parameters

  • T: object

  Parameters

  • value: T

  • Default value merger: IMerger<T> = merge

  • Optional start: IStoreStartStopNotifier<T>

  Returns Writable<T>