Custom transitions in Svelte - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the built-in fade transition from Svelte.

Svelte

import { [1] } from 'svelte/transition';

Drag options to blanks, or click blank then click option'

Aslide

Bfade

Cfly

Dscale

Attempts:

3 left

💡 Hint

Common Mistakes

Using a transition name that is not imported from 'svelte/transition'.

Forgetting to import the transition before using it.

The fade transition is imported from svelte/transition to create a fade effect.

2fill in blank

medium

Complete the code to apply a fade transition to the div when it appears or disappears.

Svelte

<div transition:[1]>{{message}}</div>

Drag options to blanks, or click blank then click option'

Afade

Bslide

Cfly

Dscale

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong transition name that was not imported.

Missing the colon after 'transition'.

The transition:fade directive applies the fade effect to the element.

3fill in blank

hard

Fix the error in the custom transition function to return the correct object shape.

Svelte

function customFade(node, { duration = 400 } = {}) {
  return {
    [1]: duration,
    css: t => `opacity: ${t}`
  };
}

Drag options to blanks, or click blank then click option'

Aduration

Bdelay

Ceasing

Dtick

Attempts:

3 left

💡 Hint

Common Mistakes

Using a property name other than 'duration' causes the transition to not work.

Forgetting to return an object with the correct keys.

The returned object must have a duration property to specify how long the transition lasts.

4fill in blank

hard

Fill both blanks to create a custom transition that changes opacity and scales the element.

Svelte

function scaleFade(node, { duration = 300 } = {}) {
  return {
    [1]: duration,
    css: t => `opacity: ${t}; transform: scale(${ [2] });`
  };
}

Drag options to blanks, or click blank then click option'

Aduration

B1 - t

Ct

Ddelay

Attempts:

3 left

💡 Hint

Common Mistakes

Using '1 - t' for scale causes the element to shrink instead of grow.

Missing the duration property or misspelling it.

The duration property sets how long the transition lasts, and t controls the scale from 0 to 1 as the transition progresses.

5fill in blank

hard

Fill all three blanks to use the custom transition with parameters in the component.

Svelte

<script>
  import { cubicOut } from 'svelte/easing';

  function customTransition(node, { delay = 0, duration = 400, easing = cubicOut } = {}) {
    return {
      [1]: delay,
      duration: duration,
      easing: easing,
      css: t => `opacity: ${t}; transform: translateX(${(1 - t) * 100}px);`
    };
  }
</script>

<div transition:customTransition={{ delay: [2], duration: [3] }}>
  Slide and fade in
</div>

Drag options to blanks, or click blank then click option'

Adelay

B100

C500

Dduration

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing delay and duration property names.

Passing numbers without curly braces in the transition directive.

The first blank is the property name delay in the returned object. The second and third blanks are the values for delay and duration passed to the transition in the component.

Practice

1. What is the main purpose of a custom transition in Svelte?

easy

A. To create unique animations when elements enter or leave the page

B. To fetch data from an API

C. To manage component state

D. To handle user input events

Solution

1. Step 1: Understand what transitions do in Svelte

   Transitions animate elements as they appear or disappear from the DOM.

2. Step 2: Identify the role of custom transitions

   Custom transitions let you define your own animation styles for these changes.

3. Final Answer:

   To create unique animations when elements enter or leave the page -> Option A

4. Quick Check:

   Custom transitions = unique enter/leave animations [OK]

Hint: Custom transitions animate element entry/exit smoothly [OK]

Common Mistakes:

• Confusing transitions with data fetching
• Thinking transitions manage state
• Mixing transitions with event handling

2. Which of the following is the correct way to define a custom transition function in Svelte?

easy

A. function fade(node) { return { delay: 300, css: t => `opacity: ${t}` }; }

B. function fade(params) { return { duration: 300, css: t => `opacity: ${t}` }; }

C. function fade() { return { duration: 300, css: t => `opacity: ${t}` }; }

D. function fade(node, params) { return { duration: 300, css: t => `opacity: ${t}` }; }

Solution

1. Step 1: Recall the custom transition function signature

   It must accept node and optionally params.

2. Step 2: Check the returned object structure

   The object should include duration and a css function using t for progress.

3. Final Answer:

   function fade(node, params) { return { duration: 300, css: t => `opacity: ${t}` }; } -> Option D

4. Quick Check:

   Function(node, params) + {duration, css} = C [OK]

Hint: Custom transition needs node param and returns duration + css [OK]

Common Mistakes:

• Omitting the node parameter
• Returning delay instead of duration
• Not using a css function with progress t

3. Given this custom transition function:

function slide(node) {
  return {
    duration: 400,
    css: t => `transform: translateX(${(1 - t) * 100}%)`
  };
}

What happens to the element when it enters the DOM using transition:slide?

medium

A. It fades in with increasing opacity

B. It slides out to the right when leaving

C. It slides in from the right to its original position

D. It instantly appears without animation

Solution

1. Step 1: Analyze the css function for entry

   The transform moves from translateX(100%) at t=0 to translateX(0%) at t=1.

2. Step 2: Understand the visual effect

   The element starts off-screen right (100%) and slides left to original place (0%).

3. Final Answer:

   It slides in from the right to its original position -> Option C

4. Quick Check:

   translateX from 100% to 0% = slide in right to left [OK]

Hint: Check transform values at t=0 and t=1 for motion direction [OK]

Common Mistakes:

• Confusing enter and leave animations
• Assuming opacity changes instead of transform
• Thinking it slides out instead of in

4. This custom transition code causes an error:

function grow(node) {
  return {
    duration: 500,
    css: t => `scale(${t})`
  };
}

What is the error and how to fix it?

medium

A. Missing 'transform:' prefix in css string; fix by returning `transform: scale(${t})`

B. Duration must be a string; fix by changing 500 to '500ms'

C. Function must return a number, not a string; fix by removing css

D. Node parameter is unused; fix by removing it

Solution

1. Step 1: Identify the CSS syntax error

   The css string lacks the CSS property name; 'scale' alone is invalid.

2. Step 2: Correct the CSS string

   It should be 'transform: scale(...)' to apply scaling properly.

3. Final Answer:

   Missing 'transform:' prefix in css string; fix by returning `transform: scale(${t})` -> Option A

4. Quick Check:

   CSS property needed before scale() [OK]

Hint: CSS string must include property name like 'transform:' [OK]

Common Mistakes:

• Returning only scale() without 'transform:'
• Using wrong duration type
• Removing needed node parameter

5. You want a custom transition that fades in and grows an element from half size to full size over 600ms. Which function correctly implements this?

hard

A. function fadeGrow(node) { return { duration: 600, css: t => `opacity: ${1 - t}; transform: scale(${t})` }; }

B. function fadeGrow(node) { return { duration: 600, css: t => `opacity: ${t}; transform: scale(${0.5 + 0.5 * t})` }; }

C. function fadeGrow(node) { return { duration: 600, css: t => `opacity: ${t}; transform: scale(${t / 2})` }; }

D. function fadeGrow(node) { return { duration: 600, css: t => `opacity: ${t}; transform: scale(${1 - t})` }; }

Solution

1. Step 1: Understand the fade and grow requirements

   Opacity should go from 0 to 1 (fade in), scale from 0.5 to 1 (grow).

2. Step 2: Check each option's css function

   function fadeGrow(node) { return { duration: 600, css: t => `opacity: ${t}; transform: scale(${0.5 + 0.5 * t})` }; } uses opacity = t (0 to 1) and scale = 0.5 + 0.5 * t (0.5 to 1), matching requirements.

3. Final Answer:

   function fadeGrow(node) { return { duration: 600, css: t => `opacity: ${t}; transform: scale(${0.5 + 0.5 * t})` }; } -> Option B

4. Quick Check:

   Opacity 0->1 and scale 0.5->1 = function fadeGrow(node) { return { duration: 600, css: t => `opacity: ${t}; transform: scale(${0.5 + 0.5 * t})` }; } [OK]

Hint: Map t from 0-1 to desired opacity and scale ranges [OK]

Common Mistakes:

• Reversing opacity or scale ranges
• Using scale starting at 0 instead of 0.5
• Mixing up increasing and decreasing values