Is it possible to create a custom lifecycle in svelte 3?

Question

I need to perform a check (eg is login is true) before rendering a page. In vuejs there is the 'beforemounting' event, but it does not exist in svelte. therefore I would like to create or emulate such an event, is it possible?

question from:https://stackoverflow.com/questions/65904278/is-it-possible-to-create-a-custom-lifecycle-in-svelte-3

Answer 1

Technically everything inside the script block is executed at component instantiation, before mounting. Additionally as the documentation states beforeUpdate will run before the first mount as well.

So, given this code:

<script>
  import { beforeUpdate, onMount }

  console.log('instantiating')

  beforeUpdate(() => console.log('beforeUpdate'))
  onMount(() => console.log('onMount'))
</script>

the output would be

instantiating
beforeUpdate
onMount