How to Fix Transition Not Working in Svelte: Simple Solutions

In Svelte, transitions won't work if the element is not conditionally rendered or if the transition directive is misused. Ensure you use transitions on elements that appear or disappear with {#if} blocks and import the transition function correctly.

Why This Happens

Transitions in Svelte only run when elements enter or leave the DOM. If you apply a transition directive to an element that is always present, the transition won't trigger. Also, forgetting to import the transition function or using it incorrectly causes no effect.

svelte

<script>
  import { fade } from 'svelte/transition';
</script>

<div transition:fade>
  Always visible content
</div>

Output

The content appears instantly with no fade effect because the element never enters or leaves the DOM.

The Fix

Wrap the element with a conditional block like {#if} so it can enter or leave the DOM. Import the transition function properly and apply it to the element inside the block. This triggers the transition when the condition changes.

svelte

<script>
  import { fade } from 'svelte/transition';
  let visible = false;
</script>

<button on:click={() => visible = !visible} aria-pressed={visible}>
  Toggle content
</button>

{#if visible}
  <div transition:fade>
    This content fades in and out
  </div>
{/if}

Output

Clicking the button toggles the content with a smooth fade transition on appear and disappear.

Prevention

Always use transitions on elements that are conditionally rendered with {#if} or similar blocks. Import transitions from 'svelte/transition' correctly. Use accessible toggles with ARIA attributes for better user experience. Test transitions in your browser DevTools to confirm they run.

Related Errors

Other common issues include:

• Using animate instead of transition for entering/leaving effects.
• Applying transitions on elements inside components that never unmount.
• Forgetting to toggle the condition that controls rendering.

Key Takeaways

Transitions only work on elements that enter or leave the DOM, so use conditional rendering.

Always import transition functions like fade from 'svelte/transition' before use.

Use {#if} blocks to control element visibility for transitions to trigger.

Test transitions by toggling conditions and checking visual effects in the browser.

Use accessible controls with ARIA attributes when toggling content visibility.