In modern web development, icons are an essential component of user interfaces. WordPress sites frequently use icon fonts (such as Font Awesome) to display various icons, but with the widespread adoption of SVG, more and more developers are starting to use SVG instead of icon fonts. Why?
- The Dashicons project by WordPress has stopped accepting new icon requests, and the Block Editor directly uses SVG to display icons.
- Elementor has specifically added options to allow users to load icons via inline SVG.
- When developing custom themes or plugins, we are also gradually replacing icon fonts with SVG.
This article will dive deep into the pros and cons of both icon fonts and SVG solutions and provide practical optimization recommendations.
How Icon Fonts Work
Icon fonts are essentially a special font file where icons are stored as glyphs. When we use icon fonts, we are actually using these special font characters. For example:
<i class="fas fa-heart"></i>This method requires loading a complete font file:
@font-face {
font-family: 'FontAwesome';
src: url('fontawesome-webfont.woff2') format('woff2');
font-weight: normal;
font-style: normal;
}How SVG Works
SVG is an XML-based vector graphic format that can be directly inlined into HTML:
<svg viewBox="0 0 24 24" width="24" height="24">
<path d="M12 21.35l-1.45-1.32C5.4 15.36 2 12.28 2 8.5 2 5.42 4.42 3 7.5 3c1.74 0 3.41.81 4.5 2.09C13.09 3.81 14.76 3 16.5 3 19.58 3 22 5.42 22 8.5c0 3.78-3.4 6.86-8.55 11.54L12 21.35z"/>
</svg>Performance Comparison and Analysis
1. Loading Performance
Icon Fonts
- Pros:
- Load once, use everywhere.
- Good browser caching effect.
- Cons:
- Requires extra HTTP requests.
- Suffers from FOIT/FOUT (flash of invisible/unstyled text) issues.
- The entire font file must be loaded, even if you only use a few icons.
SVG
- Pros:
- Can be inlined, requiring no extra HTTP requests.
- Renders immediately with no delay.
- Load only what you need.
- Cons:
- Excessive inlining can increase HTML file size.
- Each icon is a separate block of code.
2. File Size Comparison
Let’s look at a concrete example:
- Font Awesome Free (Web Fonts): ~150KB
- Single SVG icon: ~300 bytes to 1KB
- 10 inline SVG icons: ~3-10KB
3. Rendering Performance
SVG generally offers better rendering performance because:
- It can take better advantage of GPU acceleration.
- The browser doesn’t need to parse and process font files.
- It reduces the load on the text rendering engine.
Should You Use SVG or Icon Fonts?
Choosing between SVG and icon fonts requires balancing based on your specific scenario. We can use the number of icons on a page as a reference guide:
- For small sites (less than 10 icons), prioritize inline SVG.
- For medium-sized sites (10-50 icons), consider using SVG Sprites.
- For large sites (more than 50 icons), a hybrid strategy is recommended.
