Why Icon font usage in Bootsrap? - Purpose & Use Cases

The Big Idea

Discover how a simple font can replace dozens of images and make your website shine effortlessly!

The Scenario

Imagine you want to add small pictures like stars, hearts, or arrows to your website buttons and menus by drawing each shape yourself or using separate image files.

The Problem

Using separate images means you must create, resize, and manage many files. It slows down your site and makes it hard to keep icons consistent in size and color.

The Solution

Icon fonts let you use icons like letters in a special font. You can easily change their size and color with simple code, just like text, without extra image files.

Before vs After

✗ Before

<button><img src='star.png' alt='star icon'> Favorite</button>

✓ After

<button><i class='bi bi-star-fill' aria-hidden='true'></i> Favorite</button>

What It Enables

Icon fonts make adding and styling icons fast, flexible, and consistent across your whole website.

Real Life Example

On an online store, you can quickly add shopping cart, search, and user icons that scale perfectly on phones and desktops without extra images.

Key Takeaways

Managing icons as fonts saves time and reduces files.

Icons scale smoothly and match text styles easily.

Improves website speed and visual consistency.

Practice

1. What is the correct way to add a Bootstrap icon for an alarm in your HTML?

easy

A. <img src='alarm.svg' class='bi'>

B. <icon name='alarm'></icon>

C. <span class='icon-alarm'></span>

D. <i class='bi bi-alarm'></i>

Solution

1. Step 1: Understand Bootstrap icon usage

   Bootstrap icons use the i tag with classes starting with bi to display icons.

2. Step 2: Identify the correct class for alarm icon

   The alarm icon uses the class bi-alarm, so the full class is bi bi-alarm.

3. Final Answer:

   <i class='bi bi-alarm'></i> -> Option D

4. Quick Check:

   Bootstrap icon tag = <i class='bi bi-iconname'></i> [OK]

Hint: Use <i> tag with 'bi bi-iconname' classes [OK]

Common Mistakes:

• Using <icon> tag which is not valid
• Using <span> without correct classes
• Using <img> instead of icon font

2. Which of the following is the correct syntax to include a Bootstrap icon for a 'check' mark?

easy

A. <i class='bi bi-check'></i>

B. <span class='bi-check'></span>

C. <i class='bi-check'></i>

D. <icon class='bi bi-check'></icon>

Solution

1. Step 1: Recall Bootstrap icon class format

   Bootstrap icons require two classes: bi and the specific icon name like bi-check.

2. Step 2: Check the tag and classes

   The correct tag is i with both classes: bi bi-check.

3. Final Answer:

   <i class='bi bi-check'></i> -> Option A

4. Quick Check:

   Two classes: 'bi' + 'bi-iconname' on <i> tag [OK]

Hint: Always use both 'bi' and 'bi-iconname' classes [OK]

Common Mistakes:

• Using only one class instead of two
• Using wrong tag like <span> or <icon>
• Missing the 'bi' base class

3. What will be the visual result of this HTML snippet?

<i class='bi bi-alarm'></i> Alarm

medium

A. A broken image icon followed by the text 'Alarm'

B. Only the text 'Alarm' without any icon

C. A text 'Alarm' with a small alarm clock icon before it

D. An error message because i tag is invalid

Solution

1. Step 1: Understand icon font rendering

   The i tag with classes bi bi-alarm renders a scalable alarm icon before the text.

2. Step 2: Check the text placement

   The text 'Alarm' appears after the icon, so the user sees the icon followed by the word.

3. Final Answer:

   A text 'Alarm' with a small alarm clock icon before it -> Option C

4. Quick Check:

   Icon + text = icon visible before text [OK]

Hint: Icon class shows icon before text inside same element [OK]

Common Mistakes:

• Thinking icon won't show without <img>
• Assuming <i> tag is invalid
• Expecting icon after text instead of before

4. You wrote this code but the icon does not appear:

<i class='bi-alarm'></i>

What is the likely problem?

medium

A. The class 'bi-alarm' is incorrect; it should be 'icon-alarm'.

B. You forgot to include the Bootstrap Icons CSS file in your page.

C. The i tag cannot be used for icons.

D. You need to use <span> instead of <i>.

Solution

1. Step 1: Check icon class usage

   The class 'bi-alarm' alone is not enough; Bootstrap icons require both 'bi' and 'bi-alarm' classes.

2. Step 2: Verify CSS inclusion

   Even with correct classes, if the Bootstrap Icons CSS file is missing, icons won't show.

3. Final Answer:

   You forgot to include the Bootstrap Icons CSS file in your page. -> Option B

4. Quick Check:

   Missing CSS file = icons not visible [OK]

Hint: Always include Bootstrap Icons CSS file in your HTML [OK]

Common Mistakes:

• Using only one class instead of two
• Not linking the Bootstrap Icons CSS file
• Thinking <i> tag is invalid for icons

5. You want to add a responsive icon button that shows a 'trash' icon and a label 'Delete' side by side, with the icon scaling nicely on all screen sizes. Which is the best approach?

hard

A. <button class='btn btn-danger'><i class='bi bi-trash'></i> Delete</button>

B. <button class='btn btn-danger'><img src='trash.svg' alt='trash icon'> Delete</button>

C. <button class='btn btn-danger'><span class='icon-trash'></span> Delete</button>

D. <button class='btn btn-danger'><i class='icon-trash'></i> Delete</button>

Solution

1. Step 1: Choose scalable icon method

   Bootstrap icons use i tag with classes like bi bi-trash for scalable vector icons that scale well on all devices.

2. Step 2: Combine icon with button and label

   Placing the icon inside the button before the text label ensures they appear side by side and respond to button styling.

3. Final Answer:

   <button class='btn btn-danger'><i class='bi bi-trash'></i> Delete</button> -> Option A

4. Quick Check:

   Use <i> with 'bi bi-icon' inside button for responsive icons [OK]

Hint: Use inside buttons for scalable icons [OK]

Common Mistakes:

• Using <img> which may not scale well
• Using wrong classes like 'icon-trash'
• Not placing icon inside button element