davidbgk
/
larlet-fr-david-cache

<!doctype html><!-- This is a valid HTML5 document. -->
<!-- Screen readers, SEO, extensions and so on. -->
<html lang=fr>
<!-- Has to be within the first 1024 bytes, hence before the <title>
  See: https://www.w3.org/TR/2012/CR-html5-20121217/document-metadata.html#charset -->
<meta charset=utf-8>
<!-- Why no `X-UA-Compatible` meta: https://stackoverflow.com/a/6771584 -->
<!-- The viewport meta is quite crowded and we are responsible for that.
  See: https://codepen.io/tigt/post/meta-viewport-for-2015 -->
<meta name=viewport content="width=device-width,minimum-scale=1,initial-scale=1,shrink-to-fit=no">
<!-- Required to make a valid HTML5 document. -->
<title>Save-Data Usage - Web Performance Consulting | TimKadlec.com (archive) — David Larlet</title>
<!-- Generated from https://realfavicongenerator.net/ such a mess. -->
<link rel="apple-touch-icon" sizes="180x180" href="/static/david/icons/apple-touch-icon.png">
<link rel="icon" type="image/png" sizes="32x32" href="/static/david/icons/favicon-32x32.png">
<link rel="icon" type="image/png" sizes="16x16" href="/static/david/icons/favicon-16x16.png">
<link rel="manifest" href="/manifest.json">
<link rel="mask-icon" href="/static/david/icons/safari-pinned-tab.svg" color="#5bbad5">
<link rel="shortcut icon" href="/static/david/icons/favicon.ico">
<meta name="apple-mobile-web-app-title" content="David Larlet">
<meta name="application-name" content="David Larlet">
<meta name="msapplication-TileColor" content="#da532c">
<meta name="msapplication-config" content="/static/david/icons/browserconfig.xml">
<meta name="theme-color" content="#f0f0ea">
<!-- That good ol' feed, subscribe :p. -->
<link rel=alternate type="application/atom+xml" title=Feed href="/david/log/">

  <meta name="robots" content="noindex, nofollow">
  <meta content="origin-when-cross-origin" name="referrer">
  <!-- Canonical URL for SEO purposes -->
  <link rel="canonical" href="https://timkadlec.com/remembers/2019-08-29-save-data-usage/">

<style>
/* http://meyerweb.com/eric/tools/css/reset/ */
html, body, div, span,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, address, big, cite, code,
del, dfn, em, img, ins,
small, strike, strong, tt, var,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed,
figure, figcaption, footer, header, hgroup,
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
}
/* HTML5 display-role reset for older browsers */
article, aside, details, figcaption, figure,
footer, header, hgroup, menu, nav, section { display: block; }
body { line-height: 1; }
blockquote, q { quotes: none; }
blockquote:before, blockquote:after,
q:before, q:after {
  content: '';
  content: none;
}
table {
  border-collapse: collapse;
  border-spacing: 0;
}

/* http://practicaltypography.com/equity.html */
/* https://calendar.perfplanet.com/2016/no-font-face-bulletproof-syntax/ */
/* https://www.filamentgroup.com/lab/js-web-fonts.html */
@font-face {
  font-family: 'EquityTextB';
  src: url('/static/david/css/fonts/Equity-Text-B-Regular-webfont.woff2') format('woff2'),
       url('/static/david/css/fonts/Equity-Text-B-Regular-webfont.woff') format('woff');
  font-weight: 300;
  font-style: normal;
  font-display: swap;
}
@font-face {
  font-family: 'EquityTextB';
  src: url('/static/david/css/fonts/Equity-Text-B-Italic-webfont.woff2') format('woff2'),
       url('/static/david/css/fonts/Equity-Text-B-Italic-webfont.woff') format('woff');
  font-weight: 300;
  font-style: italic;
  font-display: swap;
}
@font-face {
  font-family: 'EquityTextB';
  src: url('/static/david/css/fonts/Equity-Text-B-Bold-webfont.woff2') format('woff2'),
       url('/static/david/css/fonts/Equity-Text-B-Bold-webfont.woff') format('woff');
  font-weight: 700;
  font-style: normal;
  font-display: swap;
}

@font-face {
  font-family: 'ConcourseT3';
  src: url('/static/david/css/fonts/concourse_t3_regular-webfont-20190806.woff2') format('woff2'),
       url('/static/david/css/fonts/concourse_t3_regular-webfont-20190806.woff') format('woff');
  font-weight: 300;
  font-style: normal;
  font-display: swap;
}


/* http://practice.typekit.com/lesson/caring-about-opentype-features/ */
body {
  /* http://www.cssfontstack.com/ Palatino 99% Win 86% Mac */
  font-family: "EquityTextB", Palatino, serif;
  background-color: #f0f0ea;
  color: #07486c;
  font-kerning: normal;
  -moz-osx-font-smoothing: grayscale;
  -webkit-font-smoothing: subpixel-antialiased;
  text-rendering: optimizeLegibility;
  font-variant-ligatures: common-ligatures contextual;
  font-feature-settings: "kern", "liga", "clig", "calt";
}
pre, code, kbd, samp, var, tt {
  font-family: 'TriplicateT4c', monospace;
}
em {
  font-style: italic;
  color: #323a45;
}
strong {
  font-weight: bold;
  color: black;
}
nav {
  background-color: #323a45;
  color: #f0f0ea;
  display: flex;
  justify-content: space-around;
  padding: 1rem .5rem;
}
  nav:last-child {
    border-bottom: 1vh solid #2d7474;
  }
  nav a {
    color: #f0f0ea;
  }
  nav abbr {
    border-bottom: 1px dotted white;
  }

h1 {
  border-top: 1vh solid #2d7474;
  border-bottom: .2vh dotted #2d7474;
  background-color: #e3e1e1;
  color: #323a45;
  text-align: center;
  padding: 5rem 0 4rem 0;
  width: 100%;
  font-family: 'ConcourseT3';
  display: flex;
  flex-direction: column;
}
  h1.single {
    padding-bottom: 10rem;
  }
  h1 span {
    position: absolute;
    top: 1vh;
    left: 20%;
    line-height: 0;
  }
    h1 span a {
      line-height: 1.7;
      padding: 1rem 1.2rem .6rem 1.2rem;
      border-radius: 0 0 6% 6%;
      background: #2d7474;
      font-size: 1.3rem;
      color: white;
      text-decoration: none;
    }
h2 {
  margin: 4rem 0 1rem;
  border-top: .2vh solid #2d7474;
  padding-top: 1vh;
}
h3 {
  text-align: center;
  margin: 3rem 0 .75em;
}
hr {
  height: .4rem;
  width: .4rem;
  border-radius: .4rem;
  background: #07486c;
  margin: 2.5rem auto;
}
time {
  display: bloc;
  margin-left: 0 !important;
}
ul, ol {
  margin: 2rem;
}
ul {
  list-style-type: square;
}
a {
  text-decoration-skip-ink: auto;
  text-decoration-thickness: 0.05em;
  text-underline-offset: 0.09em;
}
article {
  max-width: 50rem;
  display: flex;
  flex-direction: column;
  margin: 2rem auto;
}
  article.single {
    border-top: .2vh dotted #2d7474;
    margin: -6rem auto 1rem auto;
    background: #f0f0ea;
    padding: 2rem;
  }
  article p:last-child {
    margin-bottom: 1rem;
  }
p {
  padding: 0 .5rem;
  margin-left: 3rem;
}
  p + p,
  figure + p {
    margin-top: 2rem;
  }

blockquote {
  background-color: #e3e1e1;
  border-left: .5vw solid #2d7474;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 1rem;
  margin: 1.5rem;
}
  blockquote cite {
    font-style: italic;
  }
  blockquote p {
    margin-left: 0;
  }

figure {
  border-top: .2vh solid #2d7474;
  background-color: #e3e1e1;
  text-align: center;
  padding: 1.5rem 0;
  margin: 1rem 0 0;
  font-size: 1.5rem;
  width: 100%;
}
  figure img {
    max-width: 250px;
    max-height: 250px;
    border: .5vw solid #323a45;
    padding: 1px;
  }
figcaption {
  padding: 1rem;
  line-height: 1.4;
}
aside {
  display: flex;
  flex-direction: column;
  background-color: #e3e1e1;
  padding: 1rem 0;
  border-bottom: .2vh solid #07486c;
}
  aside p {
    max-width: 50rem;
    margin: 0 auto;
  }

/* https://fvsch.com/code/css-locks/ */
p, li, pre, code, kbd, samp, var, tt, time, details, figcaption {
  font-size: 1rem;
  line-height: calc( 1.5em + 0.2 * 1rem );
}
h1 {
  font-size: 1.9rem;
  line-height: calc( 1.2em + 0.2 * 1rem );
}
h2 {
  font-size: 1.6rem;
  line-height: calc( 1.3em + 0.2 * 1rem );
}
h3 {
  font-size: 1.35rem;
  line-height: calc( 1.4em + 0.2 * 1rem );
}
@media (min-width: 20em) {
  /* The (100vw - 20rem) / (50 - 20) part
     resolves to 0-1rem, depending on the
     viewport width (between 20em and 50em). */
  p, li, pre, code, kbd, samp, var, tt, time, details, figcaption {
    font-size: calc( 1rem + .6 * (100vw - 20rem) / (50 - 20) );
    line-height: calc( 1.5em + 0.2 * (100vw - 50rem) / (20 - 50) );
    margin-left: 0;
  }
  h1 {
    font-size: calc( 1.9rem + 1.5 * (100vw - 20rem) / (50 - 20) );
    line-height: calc( 1.2em + 0.2 * (100vw - 50rem) / (20 - 50) );
  }
  h2 {
    font-size: calc( 1.5rem + 1.5 * (100vw - 20rem) / (50 - 20) );
    line-height: calc( 1.3em + 0.2 * (100vw - 50rem) / (20 - 50) );
  }
  h3 {
    font-size: calc( 1.35rem + 1.5 * (100vw - 20rem) / (50 - 20) );
    line-height: calc( 1.4em + 0.2 * (100vw - 50rem) / (20 - 50) );
  }
}
@media (min-width: 50em) {
  /* The right part of the addition *must* be a
     rem value. In this example we *could* change
     the whole declaration to font-size:2.5rem,
     but if our baseline value was not expressed
     in rem we would have to use calc. */
  p, li, pre, code, kbd, samp, var, tt, time, details, figcaption {
    font-size: calc( 1rem + .6 * 1rem );
    line-height: 1.5em;
  }
  p, li, pre, details {
    margin-left: 3rem;
  }
  h1 {
    font-size: calc( 1.9rem + 1.5 * 1rem );
    line-height: 1.2em;
  }
  h2 {
    font-size: calc( 1.5rem + 1.5 * 1rem );
    line-height: 1.3em;
  }
  h3 {
    font-size: calc( 1.35rem + 1.5 * 1rem );
    line-height: 1.4em;
  }
  figure img {
    max-width: 500px;
    max-height: 500px;
  }
}

figure.unsquared {
  margin-bottom: 1.5rem;
}
  figure.unsquared img {
    height: inherit;
  }


@media print {
  body { font-size: 100%; }
  a:after { content: " (" attr(href) ")"; }
  a, a:link, a:visited, a:after {
    text-decoration: underline;
    text-shadow: none !important;
    background-image: none !important;
    background: white;
    color: black;
  }
  abbr[title] { border-bottom: 0; }
  abbr[title]:after { content: " (" attr(title) ")"; }
  img { page-break-inside: avoid; }
  @page { margin: 2cm .5cm; }
  h1, h2, h3 { page-break-after: avoid; }
  p3 { orphans: 3; widows: 3; }
  img {
    max-width: 250px !important;
    max-height: 250px !important;
  }
  nav, aside { display: none; }
}

ul.with_columns {
  column-count: 1;
}
@media (min-width: 20em) {
  ul.with_columns {
    column-count: 2;
  }
}
@media (min-width: 50em) {
  ul.with_columns {
    column-count: 3;
  }
}
ul.with_two_columns {
  column-count: 1;
}
@media (min-width: 20em) {
  ul.with_two_columns {
    column-count: 1;
  }
}
@media (min-width: 50em) {
  ul.with_two_columns {
    column-count: 2;
  }
}

.gallery {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-around;
}
  .gallery figure img {
    margin-left: 1rem;
    margin-right: 1rem;
  }
  .gallery figure figcaption {
    font-family: 'ConcourseT3'
  }

footer {
  font-family: 'ConcourseT3';
  display: flex;
  flex-direction: column;
  border-top: 3px solid white;
  padding: 4rem 0;
  background-color: #07486c;
  color: white;
}
  footer > * {
    max-width: 50rem;
    margin: 0 auto;
  }
  footer a {
    color: #f1c40f;
  }
  footer .avatar {
    width: 200px;
    height: 200px;
    border-radius: 50%;
    float: left;
    -webkit-shape-outside: circle();
    shape-outside: circle();
    margin-right: 2rem;
    padding: 2px 5px 5px 2px;
    background: white;
    border-left: 1px solid #f1c40f;
    border-top: 1px solid #f1c40f;
    border-right: 5px solid #f1c40f;
    border-bottom: 5px solid #f1c40f;
  }
</style>

<h1>
  <span><a id="jumper" href="#jumpto" title="Un peu perdu ?">?</a></span>
  Save-Data Usage - Web Performance Consulting | TimKadlec.com (archive)
  <time>Pour la pérennité des contenus liés. Non-indexé, retrait sur simple email.</time>
</h1>
<section>
  <article>
    <h3><a href="https://timkadlec.com/remembers/2019-08-29-save-data-usage/">Source originale du contenu</a></h3>
    <p>Yesterday someone at Shopify <a href="https://twitter.com/brend0/status/1166817897500618753?s=20">let me know on Twitter</a> that they started reducing page weight if the Save-Data header is on.</p>

<blockquote>
<p>@tkadlec <a href="http://shopify.com">http://shopify.com</a> is now Save-Data aware. About a 13% reduction in page weight, <a href="https://webpagetest.org/video/compare.php?tests=190828_NC_2480ff19108ef9d64a3cbb0a3061b15c,190828_1B_bd8a98e3b3ed3758c5586c4bc371e004">https://webpagetest.org/video/compare.php?tests=190828_NC_2480ff19108ef9d64a3cbb0a3061b15c,190828_1B_bd8a98e3b3ed3758c5586c4bc371e004</a></p>

<p>Early data shows 20% of Indian/Brazilian requests contain this header so happy days #webperf 🎉</p>
</blockquote>

<p>I love seeing companies paying attention to the Save-Data header. I’m not one to get super excited about headers normally (I <a href="https://vimeo.com/305437195">leave that to Andrew Betts</a>), but I’m pretty excited about this one.</p>

<p>The Save-Data is a header that gets passed along by a browser when the user has turned on some sort of data saving feature in that browser. Companies spend millions of dollars on surveys and research every year trying to figure out what their customers want. The Save-Data header is one of those rare times when the customers are explicitly telling us what they want: to use the site, but without using so much data.</p>

<p>There aren’t a lot of real-world examples of sites optimizing for when the Save-Data header is enabled. That’s a shame because it’s looking like it may be more common than we think.</p>

<p>In that tweet, Brendan noted that:</p>

<blockquote>
<p>Early data shows 20% of Indian/Brazilian requests contain this header so happy days #webperf 🎉</p>
</blockquote>

<p>20% is a pretty substantial number, but it’s not far off from what I’ve seen and heard from others.</p>

<p>I had someone from a large global travel company tell me that out of their roughly 6 million daily unique visitors, about 20% of them have Save-Data turned on.</p>

<p><a href="https://twitter.com/TimVereecke/status/1052166752774295553">Tim Vereecke has talked quite a bit about Save-Data</a> and how, on his site, he sees about 50% of end-users passing the header and about 10% of those having it enabled.</p>

<p>I’ve been tracking Save-Data here, on this site, using custom data in <a href="https://speedcurve.com">SpeedCurve</a>, like so:</p>

<pre><code>if ("connection" in navigator) {
    LUX.addData('save-data',navigator.connection.saveData);
}
</code></pre>

<p>So far, around ~4% of all sessions have Save-Data enabled. While nowhere near the percentage seen the companies above have seem (which makes sense, given the more focused audience) that’s still nothing to sneeze at.</p>

<p>And here’s the thing: if my site—a site read overwhelmingly by people in tech who are far more likely to have decent devices and networks—is seeing 4% of folks have Save-Data enabled, I imagine there are a lot of major publishers and e-commerce shops who are seeing a much larger percentage. They probably don’t yet realize it, but I’ll bet it’s there.</p>

<p>I would <em>love</em> to see more data on this. So please, if you have data to share, let me know!</p>

<p>Because while the web keeps getting heavier and we keep moving further away from page weight as a primary performance metric, the data I’ve seen so far indicates folks who want low-data experiences are far more common than we may think.</p>
  </article>
</section>


<nav id="jumpto">
  <p>
    <a href="/david/blog/">Accueil du blog</a> |
    <a href="https://timkadlec.com/remembers/2019-08-29-save-data-usage/">Source originale</a> |
    <a href="/david/stream/2019/">Accueil du flux</a>
  </p>
</nav>

<footer>
  <div>
    <img src="/static/david/david-larlet-avatar.jpg" loading="lazy" class="avatar" width="200" height="200">
    <p>
      Bonjour/Hi!
      Je suis <a href="/david/" title="Profil public">David&nbsp;Larlet</a>, je vis actuellement à Montréal et j’alimente cet espace depuis 15 ans. <br>
      Si tu as apprécié cette lecture, n’hésite pas à poursuivre ton exploration. Par exemple via les <a href="/david/blog/" title="Expériences bienveillantes">réflexions bimestrielles</a>, la <a href="/david/stream/2019/" title="Pensées (dés)articulées">veille hebdomadaire</a> ou en t’abonnant au <a href="/david/log/" title="S’abonner aux publications via RSS">flux RSS</a> (<a href="/david/blog/2019/flux-rss/" title="Tiens c’est quoi un flux RSS ?">so 2005</a>).
    </p>
    <p>
      Je m’intéresse à la place que je peux avoir dans ce monde. En tant qu’humain, en tant que membre d’une famille et en tant qu’associé d’une coopérative. De temps en temps, je fais aussi des <a href="https://github.com/davidbgk" title="Principalement sur Github mais aussi ailleurs">trucs techniques</a>. Et encore plus rarement, <a href="/david/talks/" title="En ce moment je laisse plutôt la place aux autres">j’en parle</a>.
    </p>
    
    <p>
      Voici quelques articles choisis :
      <a href="/david/blog/2019/faire-equipe/" title="Accéder à l’article complet">Faire équipe</a>,
      <a href="/david/blog/2018/bivouac-automnal/" title="Accéder à l’article complet">Bivouac automnal</a>,
      <a href="/david/blog/2018/commodite-effondrement/" title="Accéder à l’article complet">Commodité et effondrement</a>,
      <a href="/david/blog/2017/donnees-communs/" title="Accéder à l’article complet">Des données aux communs</a>,
      <a href="/david/blog/2016/accompagner-enfant/" title="Accéder à l’article complet">Accompagner un enfant</a>,
      <a href="/david/blog/2016/senior-developer/" title="Accéder à l’article complet">Senior developer</a>,
      <a href="/david/blog/2016/illusion-sociale/" title="Accéder à l’article complet">L’illusion sociale</a>,
      <a href="/david/blog/2016/instantane-scopyleft/" title="Accéder à l’article complet">Instantané Scopyleft</a>,
      <a href="/david/blog/2016/enseigner-web/" title="Accéder à l’article complet">Enseigner le Web</a>,
      <a href="/david/blog/2016/simplicite-defaut/" title="Accéder à l’article complet">Simplicité par défaut</a>,
      <a href="/david/blog/2016/minimalisme-esthetique/" title="Accéder à l’article complet">Minimalisme et esthétique</a>,
      <a href="/david/blog/2014/un-web-omni-present/" title="Accéder à l’article complet">Un web omni-présent</a>,
      <a href="/david/blog/2014/manifeste-developpeur/" title="Accéder à l’article complet">Manifeste de développeur</a>,
      <a href="/david/blog/2013/confort-convivialite/" title="Accéder à l’article complet">Confort et convivialité</a>,
      <a href="/david/blog/2013/testament-numerique/" title="Accéder à l’article complet">Testament numérique</a>,
      et <a href="/david/blog/" title="Accéder aux archives">bien d’autres…</a>
    </p>
    <p>
      On peut <a href="mailto:david%40larlet.fr" title="Envoyer un courriel">échanger par courriel</a>. Si éventuellement tu souhaites que l’on travaille ensemble, tu devrais commencer par consulter le <a href="http://larlet.com">profil dédié à mon activité professionnelle</a> et/ou contacter directement <a href="http://scopyleft.fr/">scopyleft</a>, la <abbr title="Société coopérative et participative">SCOP</abbr> dont je fais partie depuis six ans. Je recommande au préalable de lire <a href="/david/blog/2018/cout-site/" title="Attention ce qui va suivre peut vous choquer">combien coûte un site</a> et pourquoi je suis plutôt favorable à une <a href="/david/pro/devis/" title="Discutons-en !">non-demande de devis</a>.
    </p>
    <p>
      Je ne traque pas ta navigation mais mon
      <abbr title="Alwaysdata, 62 rue Tiquetonne 75002 Paris, +33.184162340">hébergeur</abbr>
      conserve des logs d’accès.
    </p>
  </div>
</footer>
<script type="text/javascript">
  ;(_ => {
    const jumper = document.getElementById('jumper')
    jumper.addEventListener('click', e => {
      e.preventDefault()
      const anchor = e.target.getAttribute('href')
      const targetEl = document.getElementById(anchor.substring(1))
      targetEl.scrollIntoView({behavior: 'smooth'})
    })
  })()
</script>