Task Instance

Structure

To standardize the approach regardless of which task modifier you’re using, every task modifier will use the same underlying TaskInstance structure inside of a svelte store.

A TaskInstance comprises of:

• error: if an error is thrown inside the task instance, it will be found here
• hasStarted: it is possible for the task instance to be in a queue, waiting to start. This property will change to true the instant the task instance has started
• isCanceled: whether the task instance was canceled
• isError: whether the task instance throw an error before completing
• isRunning: whether the task instance is currently running
• isSuccessful: whether the task instance completed successfully
• value: if the task instance completed successfully, this will be the return value

And for those of you that prefer to read code, here is the typing of the TaskInstance:

type TaskInstance<TReturn> = {
  /**
   * If an error is thrown inside the task instance, it will be found here.
   */
  error?: Error;

  /**
   * Indicates whether the task instance has started.
   */
  hasStarted: boolean;

  /**
   * Indicates whether the task instance was canceled.
   */
  isCanceled: boolean;

  /**
   * Indicates whether the task instance threw an error before completing.
   */
  isError: boolean;

  /**
   * Indicates whether the task instance is currently running.
   */
  isRunning: boolean;

  /**
   * Indicates whether the task instance completed successfully.
   */
  isSuccessful: boolean;

  /**
   * If the task instance completed successfully, this will be the return value.
   */
  value?: TReturn;
};

You can access these properties just as you would with any other Svelte store:

<script lang="ts">
  import { task } from '@sheepdog/svelte';

  const myTask = task(async () => {
    // your code
  });

  let lastInstance;
</script>

<button on:click={() => {
  lastInstance = myTask.perform()
  }}> Press me </button>

  {#if $lastInstance.isRunning}
    Last instance is running!
  {/if}

<button on:click={() => {
  const myInstance = myTask.perform()
  myInstance.get() // { isRunning: true, hasStarted: true, ... }
  }}> Press me </button>

Cancellation

Each task instance is also packaged with a cancel function that can be used to cancel itself.

<script lang="ts">
  import { task } from '@sheepdog/svelte';

  const myTask = task(async () => {
    // your code
  });

  let lastInstance;
</script>

<button on:click={() => {
  lastInstance = myTask.perform()
  }}> Press me </button>

<button on:click={() => {
  lastInstance?.cancel()
  }}> Cancel </button>