Svelte on Destroy

When building applications with Svelte, it's important to make sure that your components are properly cleaned up when they are no longer needed. One way to accomplish this is by using the onDestroy lifecycle event.

What is onDestroy?

onDestroy is a lifecycle event that is called when a Svelte component is about to be destroyed. This event is triggered just before the component is removed from the DOM, and it's a good place to perform any cleanup operations that may be necessary.

How to use onDestroy

To use onDestroy, you simply need to add a method with the name onDestroy to your Svelte component. This method will be called just before the component is removed from the DOM.

<script>
  export default {
    onDestroy() {
      // Perform cleanup operations here
    }
  }
</script>

Cleanup operations

The onDestroy method is a good place to perform any cleanup operations that may be necessary. For example, if you have registered an event listener in the onMount method, you should unregister that listener in the onDestroy method.

<script>
  import { onMount, onDestroy } from 'svelte';

  let count = 0;

  function handleClick() {
    count++;
  }

  onMount(() => {
    window.addEventListener('click', handleClick);
  });

  onDestroy(() => {
    window.removeEventListener('click', handleClick);
  });
</script>

Conclusion

In conclusion, onDestroy is a useful tool for making sure that your Svelte components are properly cleaned up when they are no longer needed. By using onDestroy, you can perform any necessary cleanup operations and avoid potential memory leaks in your application.