Transition parameters (duration, delay) in Svelte - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ component_behavior

intermediate

What is the visible effect of this Svelte transition code?

Consider this Svelte component snippet using a fade transition with a duration of 1000ms and a delay of 500ms:

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

<button on:click={() => visible = !visible}>Toggle</button>

{#if visible}
  <div transition:fade={{ duration: 1000, delay: 500 }}>Hello</div>
{/if}

What will the user see when toggling the visibility on?

Svelte

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

<button on:click={() => visible = !visible}>Toggle</button>

{#if visible}
  <div transition:fade={{ duration: 1000, delay: 500 }}>Hello</div>
{/if}

A The 'Hello' text appears after 0.5 seconds delay, then fades in over 1 second.

B The 'Hello' text appears immediately and fades in over 1 second.

C The 'Hello' text appears immediately and fades out over 1 second.

D The 'Hello' text appears after 1 second delay, then fades in instantly.

💡 Hint

Think about what the delay parameter does before the transition starts.

The delay parameter postpones the start of the fade effect by 500ms. After this delay, the fade transition runs for 1000ms, making the text appear gradually.

📝 Syntax

intermediate

Which option correctly sets a 2-second duration and 300ms delay for a Svelte slide transition?

Choose the correct syntax to apply a slide transition with a duration of 2000 milliseconds and a delay of 300 milliseconds.

A transition:slide({ duration: 2000, delay: 300 })

B transition:slide(duration=2000, delay=300)

C transition:slide={{ duration: 2000, delay: 300 }}

D transition:slide=[duration: 2000, delay: 300]

💡 Hint

Remember that Svelte transition parameters use double curly braces with key-value pairs.

The correct syntax uses double curly braces with an object: transition:slide={{ duration: 2000, delay: 300 }}. Other options use invalid syntax.

❓ state_output

advanced

What is the total time before the element fully appears with this transition?

Given this Svelte code snippet:

{#if show}
  <div transition:fly={{ duration: 1500, delay: 700 }}>Welcome</div>
{/if}

If show becomes true at time 0, after how many milliseconds will the element be fully visible?

Svelte

{#if show}
  <div transition:fly={{ duration: 1500, delay: 700 }}>Welcome</div>
{/if}

A 700 milliseconds

B 2200 milliseconds

C 1500 milliseconds

D 800 milliseconds

💡 Hint

Add the delay and duration times to find the total transition time.

The element waits 700ms (delay) before starting the 1500ms (duration) transition. Total time = 700 + 1500 = 2200ms.

🔧 Debug

advanced

Why does this Svelte transition not delay as expected?

Look at this Svelte code:

{#if visible}
  <div transition:fade={{ duration: 1000, delay: '500' }}>Hi</div>
{/if}

The developer expects a 500ms delay before fade starts, but the delay seems ignored. Why?

Svelte

{#if visible}
  <div transition:fade={{ duration: 1000, delay: '500' }}>Hi</div>
{/if}

A The delay value is a string instead of a number, so it is ignored.

B The fade transition does not support delay parameter.

C The duration must be a string, not a number.

D The transition must be wrapped in a function to accept parameters.

💡 Hint

Check the data type of the delay parameter.

Svelte expects delay as a number, not a string. Using a string causes the delay to be ignored.

🧠 Conceptual

expert

How do duration and delay parameters affect the lifecycle of a Svelte transition?

In Svelte transitions, what is the correct relationship between duration and delay parameters regarding the element's lifecycle during enter and leave?

A Delay controls the speed of the transition; duration postpones the element's insertion or removal.

B Duration delays the start of the transition; delay controls how long the transition runs, affecting element visibility timing.

C Delay and duration both control the total time the element stays visible before removal, but do not affect transition speed.

D Delay postpones the start of the transition; duration controls how long the transition runs after delay, affecting when the element is fully visible or removed.

💡 Hint

Think about what happens first: waiting or transitioning.

Delay waits before the transition starts. Duration is how long the transition effect lasts. Together, they determine when the element fully appears or disappears.