Svelte .set is not a function

February 22, 2023

I am trying to create a todo app with stores in svelte. But I am having an error that I wasn’t able to solve.

I have tried to use stores to manage all my all tasks data even it in not required but I wanted to see how stores work in svelte but I had an error that I don’t really know why.

//App.svelte

<script>
  import { onMount } from "svelte";
  import { tasks } from "./stores";
  import Item from "./assets/Item.svelte";

  var itemText = "";

  function addHandler() {
    var item = {
      value: itemText,
      id: Math.random(),
    };

    itemText = "";
    tasks.add(item);
    tasks.save();
  }

  onMount(() => {
    tasks.load();
  });
</script>

{#each $tasks as task (task.id)}
  <Item bind:value={task.value} />
{/each}

<input type="text" bind:value={itemText} />
<button on:click={addHandler}>Add Item</button>


//Item.svelte

<script>
    import { tasks } from "../stores.js";
    export let value = null;

  $: {
    if (value != null) {
      tasks.save();
      console.log($tasks);
    }
  }
</script>

<div>
  <input bind:value />
</div>

//stores.js
import { writable } from "svelte/store";

function list() {
  const { subscribe, set, update } = writable([]);

  return {
    subscribe,
    save: () => {
      update((items) => {
        localStorage.setItem("items", JSON.stringify(items));
        return items;
      });
    },
    add: (item) => update((items) => [...items, item]),
    remove: (item) => update((items) => items.filter((i) => i !== item)),
    load: () => {
      const items = JSON.parse(localStorage.getItem("items"));
      if (items) set(items);
    },
    update,
  };
}

Error:

export var tasks = list();

error: App.svelte:25 Uncaught TypeError: tasks.set is not a function
    at Array.item_value_binding (App.svelte:25:31)
    at Object.item_value_binding (App.svelte:4:42)
    at index.mjs:2020:31
    at HTMLInputElement.input_input_handler (Item.svelte:3:26)

Here is my code I don’t really know what is causing this problem if you can help I would be thankful