Carousel programmatic control in Bootsrap - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of programmatic control in a Bootstrap carousel?

Programmatic control lets you start, stop, or move the carousel slides using JavaScript instead of user clicks. It helps automate or customize slide changes.

beginner

Which Bootstrap JavaScript method moves the carousel to the next slide?

The carousel('next') method moves the carousel to the next slide programmatically.

beginner

How do you pause a Bootstrap carousel using JavaScript?

Use the carousel('pause') method to stop the automatic cycling of slides.

intermediate

What method would you use to jump to a specific slide index in a Bootstrap carousel?

Use carousel(index) where index is the zero-based slide number to jump directly to that slide.

intermediate

How can you listen for slide change events in a Bootstrap carousel?

You can listen to events like slide.bs.carousel and slid.bs.carousel to run code before or after a slide changes.

Which method starts the automatic cycling of a Bootstrap carousel?

A carousel('cycle')

B carousel('start')

C carousel('play')

D carousel('run')

The correct method to start automatic cycling is carousel('cycle').

How do you programmatically move a Bootstrap carousel to the previous slide?

A carousel('back')

B carousel('prev')

C carousel('previous')

D carousel('rewind')

Use carousel('prev') to move to the previous slide.

What event fires after a Bootstrap carousel slide has finished transitioning?

A transitionend.bs.carousel

B slide.bs.carousel

C changed.bs.carousel

D slid.bs.carousel

The slid.bs.carousel event fires after the slide transition completes.

Which argument lets you jump to a specific slide index in a Bootstrap carousel?

A carousel(index)

B carousel('jump', index)

C carousel('slideTo', index)

D carousel('go', index)

You pass the slide index directly like carousel(index) to jump to that slide.

How do you pause the automatic cycling of a Bootstrap carousel?

A carousel('stop')

B carousel('halt')

C carousel('pause')

D carousel('freeze')

Use carousel('pause') to pause the carousel.

Explain how to control a Bootstrap carousel using JavaScript methods.

Think about methods that start, stop, and move slides.

Describe how to listen for slide change events in a Bootstrap carousel and why it might be useful.

Events help react to slide changes.

Practice

1. What does programmatic control of a Bootstrap carousel allow you to do?

easy

A. Move slides using JavaScript commands

B. Change the carousel's color scheme

C. Add new images to the carousel dynamically

D. Automatically resize the carousel on window resize

Solution

1. Step 1: Understand programmatic control meaning

   Programmatic control means controlling the carousel with code, not just user clicks.

2. Step 2: Identify what JavaScript commands do

   JavaScript commands let you move slides forward, backward, or jump to a specific slide.

3. Final Answer:

   Move slides using JavaScript commands -> Option A

4. Quick Check:

   Programmatic control = move slides with code [OK]

Hint: Programmatic means controlling with code, not style [OK]

Common Mistakes:

• Confusing programmatic control with styling changes
• Thinking it adds images automatically
• Assuming it resizes carousel automatically

2. Which JavaScript method correctly moves a Bootstrap carousel to the next slide?

easy

A. carousel.next()

B. document.carousel.nextSlide()

C. carousel.slideNext()

D. $('#carouselExample').carousel('next')

Solution

1. Step 1: Recall Bootstrap carousel JavaScript syntax

   Bootstrap uses jQuery style calls like $('#id').carousel('method').

2. Step 2: Identify correct method for next slide

   The method to go to next slide is 'next', so $('#carouselExample').carousel('next') is correct.

3. Final Answer:

   $('#carouselExample').carousel('next') -> Option D

4. Quick Check:

   Use $('#id').carousel('next') to move next [OK]

Hint: Bootstrap carousel uses $('#id').carousel('method') syntax [OK]

Common Mistakes:

• Using non-existent methods like carousel.next()
• Trying to call methods on document.carousel
• Using camelCase method names not in Bootstrap API

3. Given this code snippet, what slide will be shown after execution?

$('#myCarousel').carousel(2);

Assuming the carousel has 4 slides indexed 0 to 3.

medium

A. Slide 0

B. Slide 1

C. Slide 2

D. Slide 3

Solution

1. Step 1: Understand carousel method with number argument

   Calling carousel(n) moves the carousel to slide number n (zero-based index).

2. Step 2: Identify which slide index 2 refers to

   Index 2 means the third slide (0,1,2), so slide 2 will be shown.

3. Final Answer:

   Slide 2 -> Option C

4. Quick Check:

   carousel(2) shows slide index 2 [OK]

Hint: carousel(n) jumps to slide n (zero-based) [OK]

Common Mistakes:

• Thinking carousel(2) moves 2 slides forward
• Confusing slide numbers starting at 1
• Assuming carousel(2) triggers next slide

4. What is wrong with this code to pause a Bootstrap carousel?

document.getElementById('carouselExample').carousel('pause');

medium

A. The method name should be 'stop' instead of 'pause'

B. carousel method is not available on DOM element directly

C. Missing parentheses after 'carousel'

D. The ID selector should use '#' in getElementById

Solution

1. Step 1: Understand how Bootstrap carousel methods are called

   Bootstrap carousel methods are called on jQuery objects, not plain DOM elements.

2. Step 2: Identify why getElementById fails

   getElementById returns a DOM element without jQuery methods, so .carousel('pause') is undefined.

3. Final Answer:

   carousel method is not available on DOM element directly -> Option B

4. Quick Check:

   Use jQuery selector, not getElementById, for carousel methods [OK]

Hint: Use jQuery selector $('#id'), not getElementById, for carousel [OK]

Common Mistakes:

• Trying to call carousel on plain DOM element
• Using wrong method name 'stop' instead of 'pause'
• Adding '#' inside getElementById argument

5. You want to programmatically jump to the last slide of a Bootstrap carousel with 5 slides. Which code snippet correctly does this?

hard

A. $('#carouselExample').carousel(4);

B. $('#carouselExample').carousel('last');

C. $('#carouselExample').carousel('to', 5);

D. $('#carouselExample').carousel.slide(5);

Solution

1. Step 1: Determine last slide index for 5 slides

   Slides are zero-indexed, so last slide index is 4 (0 to 4).

2. Step 2: Use correct method to jump to slide by index

   Calling carousel(4) jumps to slide index 4. Other options use invalid methods or indexes.

3. Final Answer:

   $('#carouselExample').carousel(4); -> Option A

4. Quick Check:

   Use carousel(lastIndex) to jump to last slide [OK]

Hint: Last slide index = total slides - 1; use carousel(index) [OK]

Common Mistakes:

• Using 'last' as method which doesn't exist
• Passing slide number out of range (5 instead of 4)
• Using non-existent carousel.slide() method