The ‘font-display’ Property: Controlling How Fonts are Displayed While They Load.

The ‘font-display’ Property: Controlling How Fonts are Displayed While They Load (A Humorous Lecture)

Alright class, settle down, settle down! No chewing gum, and put away those fidget spinners. Today, we embark on a thrilling, edge-of-your-seat journey… into the world of font-display! 🎉

I know, I know, you’re thinking, "Font display? Professor, is this really more exciting than watching paint dry?" And to that, I say, "YES! Absolutely! Because with font-display, you can control how the paint dries… metaphorically, of course. We’re talking about fonts, people!"

So, grab your metaphorical pencils (or, you know, actual pencils if you’re into that sort of thing) and let’s dive in.

The Problem: The Dreaded FOUT & FOIT

Before we get to the superhero that is font-display, we need to understand the villains it’s designed to defeat: the dreaded FOUT and FOIT. These aren’t some obscure Marvel villains, but rather, acronyms that strike fear into the hearts of web developers everywhere.

• FOUT (Flash Of Unstyled Text): Imagine this: you visit a website, and for a brief, agonizing moment, all the text is displayed in a basic, system font (like Times New Roman 🤮). Then, BAM!, your custom font finally loads, and everything shifts and rearranges. That, my friends, is FOUT. It’s jarring, it’s ugly, and it makes your carefully crafted design look like it had a stroke.

• FOIT (Flash Of Invisible Text): Even worse! You visit a website, and nothing appears where your custom font should be. Just… emptiness. Void. The website is playing hide-and-seek with your content! Then, after an excruciatingly long wait, your fancy font finally loads, and the text pops into existence. That’s FOIT. It’s frustrating, confusing, and makes users think your website is broken. 😱

Essentially, both FOUT and FOIT are caused by the browser waiting for a custom font to download before displaying the text. And in our instant-gratification, speed-obsessed world, waiting is simply unacceptable! 🐌

Enter the Hero: font-display

Fear not, dear students! For there is a solution! font-display is a CSS property that allows you to control how the browser handles custom fonts while they are loading. It gives you the power to choose a strategy that balances user experience with your design aesthetic. It’s like having a font-loading Swiss Army knife! 🪖

The font-display Values: Your Arsenal of Options

font-display offers several values, each with its own unique approach to the FOUT/FOIT problem. Let’s explore them one by one:

1. auto: This is the default behavior. The browser decides what to do, usually based on its default font loading strategy. In most cases, this leads to either FOUT or FOIT. Think of it as letting the browser roll the dice… and you usually lose. 🎲 (Not recommended!)

2. block: This value gives the font a short "block period" followed by an infinite "swap period."

   • Block Period: The browser hides the text for a short period (typically 3 seconds). If the font loads during this period, it’s used immediately.
   • Swap Period: If the font doesn’t load during the block period, the browser displays the text in a fallback font. Once the custom font eventually loads, it’s swapped in.

   block prioritizes preventing FOUT initially, but it can lead to FOIT if the font takes too long to load. It’s like saying, "I’d rather show nothing than something ugly… for a little while." ⏳

   Visual Representation:

   Time	Behavior
   0 – 3 seconds	Text is hidden (FOIT)
   3+ seconds	Text displayed in fallback font (FOUT)
   Font Loads	Text swapped to custom font

3. swap: This value gives the font a zero-second "block period" followed by an infinite "swap period."

   • Block Period: There is essentially no block period.
   • Swap Period: The browser immediately displays the text in a fallback font. Once the custom font loads, it’s swapped in.

   swap prioritizes displaying content as quickly as possible, even if it means a FOUT later on. It’s like saying, "I’d rather show something than nothing, even if it’s not perfect." 💨

   Visual Representation:

   Time	Behavior
   0+ seconds	Text displayed in fallback font (FOUT)
   Font Loads	Text swapped to custom font

4. fallback: This value gives the font a very short "block period" followed by a short "swap period."

   • Block Period: The browser hides the text for a very short period (even shorter than block, typically around 100ms).
   • Swap Period: If the font doesn’t load during the block period, the browser displays the text in a fallback font for a short time (typically 3 seconds). If the custom font loads during this swap period, it’s swapped in. After the swap period, the fallback font is permanently used.

   fallback tries to strike a balance between preventing FOIT and minimizing the impact of FOUT. It’s like saying, "Let’s try to load the custom font quickly, but if it takes too long, just stick with the fallback." ⚖️

   Visual Representation:

   Time	Behavior
   0 – 100ms	Text is hidden (FOIT – but very brief)
   100ms – 3s	Text displayed in fallback font (FOUT)
   Font Loads (within 3s)	Text swapped to custom font
   3+ seconds	Text remains in fallback font (Custom font ignored)

5. optional: This value tells the browser that the font is optional. It’s given a very short "block period" and a zero-second "swap period."

   • Block Period: The browser hides the text for a very short period (similar to fallback, around 100ms).
   • Swap Period: There is no swap period. If the font doesn’t load almost immediately, it’s not used at all.

   optional is best for fonts that aren’t critical to the user experience, like decorative fonts or fonts used for specific elements that aren’t essential. It’s like saying, "This font would be nice, but if it’s not readily available, no big deal." 😎

   Visual Representation:

   Time	Behavior
   0 – 100ms	Text is hidden (FOIT – but very brief)
   100+ ms	Text remains in fallback font (Custom font ignored)

Putting it into Practice: The CSS Code

Okay, enough theory! Let’s see how this works in actual code. You need to define the font-display property within your @font-face rule.

@font-face {
  font-family: 'MyCustomFont';
  src: url('mycustomfont.woff2') format('woff2'),
       url('mycustomfont.woff') format('woff'); /* Add other formats for better compatibility */
  font-weight: normal;
  font-style: normal;
  font-display: swap; /* Choose your value here! */
}

body {
  font-family: 'MyCustomFont', sans-serif; /* Use the custom font, with a fallback */
}

Explanation:

• @font-face: This rule defines a custom font.
• font-family: The name you’ll use to reference the font in your CSS.
• src: The URL(s) to your font files. Important: Provide multiple font formats (woff2, woff, ttf, etc.) for better browser compatibility.
• font-weight and font-style: Standard font properties.
• font-display: This is the magic! Set it to auto, block, swap, fallback, or optional to control the font loading behavior.
• body { font-family: ... }: Apply your custom font to the desired elements, remembering to include a system font as a fallback.

Choosing the Right Value: It Depends!

So, which font-display value should you use? The answer, as with most things in web development, is… it depends! 🤷

Here’s a handy (and slightly humorous) guide:

• swap: Use this when you absolutely, positively must show content immediately. This is a good choice for body text, headlines, or anything that’s critical for the user to see right away. Be prepared for a potential FOUT, but at least the user won’t be staring at a blank screen. Think: "Content first, style later!" 🚀

• block: Use this when the specific font is crucial to the design and a FOUT would be particularly jarring. This is a good choice for logos, brand-specific fonts, or elements where visual consistency is paramount. However, be mindful of the FOIT. Don’t make users wait too long! Think: "Style is king (but don’t be a tyrant)!" 👑

• fallback: Use this when you want a compromise. It’s a good choice for fonts that are important but not absolutely essential. It tries to minimize both FOIT and FOUT. Think: "Let’s play it safe." 🛡️

• optional: Use this for decorative fonts or elements that aren’t critical to the user experience. If the font loads quickly, great! If not, no worries. Think: "Nice to have, but not a necessity." ✨

• auto: Just… don’t. Unless you really trust the browser’s judgment (which, let’s be honest, you probably shouldn’t). 🙈

Beyond the Basics: Optimizing Font Loading

font-display is a powerful tool, but it’s just one piece of the font-loading puzzle. Here are a few extra tips for optimizing your font loading strategy:

• Use Web Font Formats: Use modern web font formats like WOFF2 for optimal compression and browser support.

• Font Subsetting: Only include the characters you actually need in your font files. This can significantly reduce their size. There are online tools available for font subsetting.

• Preload Fonts: Use <link rel="preload"> to tell the browser to download the font as early as possible. This can help reduce FOIT.

  <link rel="preload" href="mycustomfont.woff2" as="font" type="font/woff2" crossorigin>

  • as="font": Specifies that you are preloading a font.
  • type="font/woff2": Specifies the font type.
  • crossorigin: Required if the font is served from a different domain.

• Use a CDN (Content Delivery Network): CDNs can serve your fonts from servers located closer to your users, reducing latency and improving download speeds.

• Test, Test, Test: Test your website on different browsers, devices, and network conditions to see how your font loading strategy performs.

Common Mistakes to Avoid

• Forgetting the Fallback Font: Always specify a fallback font in your font-family declaration. This ensures that something is displayed while the custom font is loading (or if it fails to load altogether).

  body {
    font-family: 'MyCustomFont', sans-serif; /* 'sans-serif' is the fallback */
  }

• Using Too Many Fonts: Each font you use adds to the page’s overall load time. Stick to a limited number of fonts to keep your website lean and fast.

• Ignoring Font Optimization: Don’t just throw fonts onto your website without optimizing them. Use web font formats, subset your fonts, and preload them for the best performance.

Conclusion: Font-tastic Results!

Congratulations, class! You’ve survived the lecture on font-display! You are now armed with the knowledge to conquer FOUT and FOIT and create websites that are both visually appealing and user-friendly.

Remember:

• font-display is your weapon against font-loading woes.
• Choose the right value based on your specific needs and priorities.
• Optimize your fonts for the best performance.
• And most importantly, test, test, test!

Now go forth and create font-tastic websites! And try not to cause too many FOUTs along the way. 😉

(Class dismissed!) 🚶‍♀️ 🚶‍♂️