Transition parameters (duration, delay) in Svelte - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the duration parameter control in a Svelte transition?

The duration parameter sets how long the transition animation lasts, measured in milliseconds.

beginner

How does the delay parameter affect a Svelte transition?

The delay parameter sets how long Svelte waits before starting the transition, measured in milliseconds.

beginner

Show the syntax to apply a fade transition with a 500ms duration and 200ms delay in Svelte.

Use transition:fade={{ duration: 500, delay: 200 }} on the element to set a fade that lasts 500ms and starts after 200ms.

intermediate

Why would you use a delay in a transition?

Delay helps to wait before the animation starts, useful for sequencing animations or avoiding abrupt changes.

beginner

Can you combine duration and delay in one transition? How?

Yes, by passing an object with both properties like { duration: 400, delay: 100 } inside the transition directive.

What unit do duration and delay use in Svelte transitions?

A Milliseconds

B Seconds

C Frames

D Percentage

Both duration and delay are measured in milliseconds in Svelte transitions.

If you want a transition to start immediately but last 1 second, what should you set?

A duration: 1000, delay: 1000

B duration: 0, delay: 1000

C duration: 1000, delay: 0

D duration: 0, delay: 0

Setting delay: 0 means no wait before start, and duration: 1000 means the animation lasts 1 second.

What happens if you set a delay longer than the duration?

A The transition is ignored

B The transition runs instantly

C The transition duration doubles

D The transition waits longer before starting than it takes to finish

Delay controls wait time before start; duration controls how long the animation runs after starting.

Which is the correct way to add a fade transition with 300ms delay and 700ms duration?

A transition:fade={{ delay: 300, duration: 700 }}

B transition:fade={{ duration: 300, delay: 700 }}

C transition:fade={{ delay: 700, duration: 300 }}

D transition:fade={{ duration: 1000 }}

The object keys must match the intended delay and duration values.

Why might you want to use a delay in a transition?

A To stop the animation

B To start the animation after a pause

C To change the color of the element

D To make the animation faster

Delay adds a pause before the animation begins, useful for timing effects.

Explain how to control the timing of a Svelte transition using duration and delay parameters.

Think about waiting and running times for animations.

Describe a real-life example where adding a delay to a transition would improve user experience.

Imagine waiting your turn in a conversation.

Practice

1. In Svelte, what does the duration parameter control in a transition?

easy

A. How long to wait before starting the animation

B. The size of the animated element

C. The color of the animated element

D. How long the animation lasts

Solution

1. Step 1: Understand transition parameters

   The duration parameter defines the length of time the animation runs.

2. Step 2: Differentiate from delay

   The delay parameter controls waiting time before animation starts, not duration.

3. Final Answer:

   How long the animation lasts -> Option D

4. Quick Check:

   duration = animation length [OK]

Hint: Duration means how long animation runs, not when it starts [OK]

Common Mistakes:

• Confusing duration with delay
• Thinking duration changes color or size
• Mixing up parameter names

2. Which of the following is the correct syntax to set a 500ms delay in a Svelte transition?

easy

A. transition:fade(delay: 500)

B. transition:fade(delay=500)

C. transition:fade={{ delay: 500 }}

D. transition:fade({ delay 500 })

Solution

1. Step 1: Recall Svelte transition syntax

   Transition parameters are passed as an object inside double curly braces, e.g., transition:fade={{ delay: 500 }}.

2. Step 2: Identify correct object syntax

   transition:fade={{ delay: 500 }} uses correct object syntax with colon and braces; others have invalid syntax.

3. Final Answer:

   transition:fade={{ delay: 500 }} -> Option C

4. Quick Check:

   Use double braces and colon for parameters [OK]

Hint: Use double curly braces and colon for transition params [OK]

Common Mistakes:

• Using parentheses instead of braces
• Missing colon between key and value
• Incorrect object syntax

3. What will happen when this Svelte code runs?

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

medium

A. The div fades in after 0.5 seconds and the fade lasts 1 second

B. The div fades in immediately over 1 second

C. The div fades in after 1 second and the fade lasts 0.5 seconds

D. The div fades in instantly with no animation

Solution

1. Step 1: Understand delay and duration

   The delay: 500 means wait 500ms before starting the fade.

2. Step 2: Understand duration effect

   The duration: 1000 means the fade animation lasts 1000ms (1 second).

3. Final Answer:

   The div fades in after 0.5 seconds and the fade lasts 1 second -> Option A

4. Quick Check:

   delay = wait, duration = animation length [OK]

Hint: Delay waits before animation; duration controls animation length [OK]

Common Mistakes:

• Mixing up delay and duration values
• Assuming animation starts immediately
• Ignoring delay effect

4. Identify the error in this Svelte transition code:

<div transition:fade={{ duration: '1000', delay: 200 }}>Hi</div>

medium

A. Missing parentheses around parameters

B. Duration should be a number, not a string

C. Fade transition does not accept parameters

D. Delay cannot be less than 500

Solution

1. Step 1: Check parameter types

   Duration and delay must be numbers, not strings. Here, duration is a string '1000'.

2. Step 2: Validate other options

   Delay can be any number >= 0; fade accepts parameters; no parentheses needed.

3. Final Answer:

   Duration should be a number, not a string -> Option B

4. Quick Check:

   Use numbers for duration and delay [OK]

Hint: Use numbers, not strings, for duration and delay [OK]

Common Mistakes:

• Putting numbers in quotes
• Assuming delay minimum is 500
• Adding unnecessary parentheses

5. You want a Svelte element to fade in with a 2-second animation but only start after 1 second delay. Which code correctly achieves this?

hard

A. <div transition:fade={{ duration: 2000, delay: 1000 }}>Content</div>

B. <div transition:fade={{ delay: 2000, duration: 1000 }}>Content</div>

C. <div transition:fade={{ duration: '2000', delay: '1000' }}>Content</div>

D. <div transition:fade={{ duration: 1000 }} delay=2000>Content</div>

Solution

1. Step 1: Match duration and delay values

   Duration should be 2000ms (2 seconds), delay should be 1000ms (1 second).

2. Step 2: Check syntax correctness

   <div transition:fade={{ duration: 2000, delay: 1000 }}>Content</div> uses correct syntax with numbers and proper object format.

3. Step 3: Identify errors in other options

   Using strings like '2000' and '1000' for duration and delay is incorrect (must be numbers); swapping to {{ delay: 2000, duration: 1000 }} is wrong; placing delay=2000 outside the transition directive is invalid.

4. Final Answer:

   <div transition:fade={{ duration: 2000, delay: 1000 }}>Content</div> -> Option A

5. Quick Check:

   Correct values and syntax for delay and duration [OK]

Hint: Duration = animation length; delay = wait time before start [OK]

Common Mistakes:

• Swapping delay and duration values
• Using strings instead of numbers
• Placing delay outside transition directive