fel presentation

Web Fonts vs Web Performance

@ianfeather - Front End London, May 2013

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Friday, 31 May 13

Friday, 31 May 13

Friday, 31 May 13

Friday, 31 May 13

Friday, 31 May 13

How Critical is Critical?

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Friday, 31 May 13

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Why are fonts critical?

• FOUT, what is it?

• Where did it come from?

• How big a deal is it?

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The Browser

• Leverage them!

• They do your work for you

• But... you don’t always have to agree with them

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“...user agents may render text as it would be rendered if downloadable font resources are not available or they may render text transparently with fallback fonts to avoid a flash of text using a fallback font.”

The Spec

In cases where the font download fails user agents must display text, simply leaving transparent text is considered non-conformant behavior.”

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The Implementation

IE FF Chrome, Safari, Opera (2.15)

Text rendered immediately then repainted later

Invisible Text

3s Timeout

Invisible Text

No Timeout

PS. They’re working on it...https://bugs.webkit.org/show_bug.cgi?id=25207 ~ 2009https://code.google.com/p/chromium/issues/detail?id=235303 ~ 2013

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What are our options?

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Font Serving Services

• JS Options e.g. Typekit

• Google Web Font Loaderhttp://www.slideshare.net/clagnut/responsive-web-fonts

• Self hosted

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What’s in a font?

TypeTool, Font Forge, Glyphs & Glyphs MiniFriday, 31 May 13

Subset your font

Don’t forget the LegalsFriday, 31 May 13

Add Icons

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Choose your weapon

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Implementation Techniques(On & Off the Critical Path)

1. Synchronous, external

2. Synchronous, inline

3. Simple async solution

4. Local Storage async

5. Async and defer to 2nd page

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Synchronous, external

@font-face { font-family: 'MyWebFont'; src: url('webfont.eot'); /* IE9 Compat Modes */ src: url('webfont.eot?#iefix') format('embedded-opentype'), /* IE6-IE8 */ url('webfont.woff') format('woff'), /* Modern Browsers */ url('webfont.ttf') format('truetype'), /* Safari, Android, iOS */ url('webfont.svg#svgFontName') format('svg'); /* Legacy iOS */ }

http://www.fontsquirrel.com/tools/webfont-generator

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Synchronous, inline• WOFF can be base64 encoded and inlined.

• Slower perceived speed

• Don’t serve it to IE!

<!--[if (gt IE 8) | (IEMobile)]><!--> <link href="common_core_with_base64.css" media="all" rel="stylesheet" type="text/css" /><!--<![endif]-->

<!--[if (lt IE 9) & (!IEMobile)]> <link href="common_core_without_base64.css" media="all" rel="stylesheet" type="text/css" /><![endif]-->

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Simple Async var f, x;

x = document.getElementsByTagName("script")[0];

f = window.document.createElement("link");

f.rel = "stylesheet";

f.href = "#{asset_path("woff.css")}"; window.setTimeout(function(){ x.parentNode.insertBefore(f, x); },0)

• Don’t forget to factor in non-woff versions

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Local Storage Async

• Uses the browser Local Storage rather than HTTP Cache

• A solution by the Guardian Team (https://github.com/guardian/frontend/blob/master/common/app/assets/javascripts/modules/fonts.js)

• Loads the font with (well controlled) FOUT

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Async & Defer // HEADER if fonts_are_cached do <link href=”woff.css” rel=”stylesheet” /> end

// FOOTER if !fonts_are_cached do <script> // Load in custom fonts $.ajax({ url: '#{asset_path("woff.css")}', success: function () { // Set cookie } }); </script> end

Read more: http://css-tricks.com/preventing-the-performance-hit-from-custom-fonts/

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Which is difficult if you’ve added icons...

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What next?

• Client hints, connectionType and its blatant misuse

• Browsers giving authors the option of how to render a custom font

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Thanks, any questions?

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