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Como Perder Peso (no browser)
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Zeno Rocha
March 09, 2013
Technology
52
11k
Como Perder Peso (no browser)
Presented at Rio.JS Conf
March 9, 2013
Rio de Janeiro, Brazil
Zeno Rocha
March 09, 2013
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Transcript
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hoje vamos falar de performance
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“Otimize a performance do front-end primeiro, é onde 80/90% do
tempo de resposta ao usuário é gasto.” - Steve Souders
http://googlewebmastercentral.blogspot.com.br/2010/04/using-site-speed-in-web-search-ranking.html
None
• Economizar 1kb significa: • Em 60 segundos = 3.4GB
Fonte: http://jaydson.org/talks/x-web-performance/
• Economizar 1kb significa: • Em 1 hora = 180GB
Fonte: http://jaydson.org/talks/x-web-performance/
• Economizar 1kb significa: • Em 1 dia = 4.2TB
Fonte: http://jaydson.org/talks/x-web-performance/
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• + 15.000.000 de acessos por dia • De 3mb
para 267kb • De 7.5s para 4.3s Fonte: http://www.slideshare.net/keppelen/performance-frontend-front-in-macei/
• Diminuir 3.2s resultou em: • Redução de custo em
servidores de R$ 16.000,00 por dia Fonte: http://www.slideshare.net/keppelen/performance-frontend-front-in-macei/
• Diminuir 3.2s resultou em: • Aumento de receita de
R$ 1.000.000,00 por dia Fonte: http://www.slideshare.net/keppelen/performance-frontend-front-in-macei/
html CSS imagens servidor jquery JS
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html
#27 evite códigos inline
inline #27 <style> .center { width: 960px; margin: 0 auto;
} </style> - requisições +tamanho
externo #27 <link rel="stylesheet" href="main.css"> + organização - tamanho +
cache
#26 estilos no topo, scripts no rodapé
#26 <!doctype html> <html> <head> <meta charset="UTF-8"> <title>Browser Diet</title> <!--
CSS --> <link rel="stylesheet" href="style.css"> </head>
#26 <body> <p>Lorem ipsum dolor sit amet.</p> <!-- JS -->
<script src="script.js"></script> </body> </html>
comprima seu html #25
normal #25 <p>Lorem ipsum dolor sit amet.</p> <!-- My List
--> <ul> <li><a href="#"></a></li> <li><a href="#"></a></li> <li><a href="#"></a></li> </ul>
#25 <p>Lorem ipsum dolor sit amet.</ p><ul><li><a href="#"></a></li><li><a href="#"></a></li><li><a href="#"></a></
li></ul> comprimido
https://code.google.com/p/htmlcompressor/
https://github.com/jney/grunt-htmlcompressor
#24 experimente async & defer
#24 script normal <script src="example.js"></script>
#24 script async <script async src="example.js"></script> +ie10
#24 script defer <script defer src="example.js"></script> +ie5
CSS
comprima seu css #23
normal #23 .center { width: 960px; margin: 0 auto; }
/* --- Structure --- */ .intro { margin: 100px; }
#23 comprimido .center{width:960px;margin:0 auto;}.intro{margin: 100px;position:relative;}
http://yui.github.com/yuicompressor/
http://www.cssminifier.com/
https://github.com/jzaefferer/grunt-css
combine vários arquivos em um só #22
#22 <link rel="stylesheet" href="structure.css"> <link rel="stylesheet" href="banner.css"> <link rel="stylesheet" href="layout.css">
<link rel="stylesheet" href="component.css"> <link rel="stylesheet" href="all.css"> vs
http://yui.github.com/yuicompressor/
http://www.cssminifier.com/
https://github.com/jzaefferer/grunt-css
não use seletor universal #21
* { margin: 0; padding: 0; border: none; text-decoration: none;
outline: 0; } #21
http://meyerweb.com/eric/tools/css/reset/
http://necolas.github.com/normalize.css/
prefira <link> ao @import #20
<link rel="stylesheet" href="style.css"> #20 vs @import url('style.css');
pense e repense seu key selector #19
key selector >> a header nav ul li a {}
#19
key selector header nav ul li * { /* Péssimo
*/ } header nav ul li a { /* Muito Ruim */ } nav a { /* Ruim */ } nav a.nav-link { /* Bom */ } nav .nav-link { /* Ótimo */ } .nav-link { /* Excelente */ } #19
JAVASCRIPT
códigos de terceiros? sempre assíncronos #18
async var script = document.createElement('script'), scripts = document.getElementsByTagName('script')[0]; script.async =
true; script.src = url; scripts.parentNode.insertBefore(script, #18
guarde o tamanho do array #17
ruim... var arr = new Array(1000); for (var i =
0; i < arr.length; i++) { // O tamanho do array é calculado 1000 } #17
bom! var arr = new Array(1000); for (var i =
0, len = arr.length; i < len; i++) { // O tamanho só é calculado 1 vez e armazenado } #17
http://jsperf.com/browser-diet-cache-array-length
http://jsperf.com/browser-diet-cache-array-length
evite o document.write #16
html5 boilerplate <script src="//ajax.googleapis.com/ajax/libs/ jquery/1.9.0/jquery.min.js"></script> <script>window.jQuery || document.write('<script src="js/vendor/jquery-1.9.0.min.js"><\/ script>')</script>
#16
minimize repaints e reflows #15
ruim... var myList = document.getElementById("myList"); for (var i = 0;
i < 100; i++) { myList.innerHTML += "<span>" + i + "</span>"; } #15
var myList = ""; for (var i = 0; i
< 100; i++) { myList += "<span>" + i + "</span>"; } document.getElementById("myList").innerHTML = myList; bom! #15
http://jsperf.com/browser-diet-dom-manipulation
http://jsperf.com/browser-diet-dom-manipulation
comprima seu js #14
normal #14 BrowserDiet.app = function() { var foo = true;
return { bar: function() { // do something } }; };
comprimido BrowserDiet.app=function() {return{bar:function(){}}}; #14
http://yui.github.com/yuicompressor/
https://developers.google.com/closure/compiler/?hl=pt
https://github.com/mishoo/UglifyJS
combine vários arquivos em um só #13
#13 <script src="navbar.js"></script> <script src="component.js"></script> <script src="page.js"></script> <script src="framework.js"></script> <script
src="all.js"></script> vs
http://gruntjs.com/
jquery
use sempre a última versão #12
<script src="http://code.jquery.com/jquery-latest.js"></script> #12 vs <script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
seletores #11
#11 find children .class #id context
#11 $("#foo"); id é mais rapido
http://jsperf.com/browser-diet-jquery-selectors
http://jsperf.com/browser-diet-jquery-selectors
abuse do encadeamento #10
não encadeando $("#object").addClass("foo"); $("#object").css("border-color","#f0f"); $("#object").width(200); $("#object").removeClass("bar"); #10
encadeando $("#object").addClass("foo").css("border-color", "#ccc").width(200).addClass("bar"); #10
http://jsperf.com/browser-diet-chaining
http://jsperf.com/browser-diet-chaining
use for ao invés de each #9
#9 while reverso for $.each for in
#9 for ( var i = 0, len = a.length;
i < len; i++ ) { e = a[i]; } for é mais rapido
http://jsperf.com/browser-diet-jquery-each-vs-for-loop
http://jsperf.com/browser-diet-jquery-each-vs-for-loop
não use jquery #8
jquery $('a').on('click', function() { console.log( $(this).attr('id') ); }); #8
js puro $('a').on('click', function() { console.log( this.id ); }); #8
http://jsperf.com/browser-diet-this-attr-id-vs-this-id
http://jsperf.com/browser-diet-this-attr-id-vs-this-id
imagens
css sprites #7
imagem #7
css #7 .icon-foo { background-image: url('mySprite.png'); background-position: -10px -10px; }
.icon-bar { background-image: url('mySprite.png'); background-position: -5px -5px; }
http://wearekiss.com/spritepad
http://www.spritecow.com/
http://compass-style.org/help/tutorials/spriting/
não escale as imagens direto no código #6
html #6 <img width="100" height="100" src="logo.jpg" alt="Logo">
otimize as imagens #5
#5 lossless png 8 png 24 jpg gif
servidor
habilite o caches dos arquivos #4
.htaccess #4 ExpiresActive On ExpiresByType image/gif "access plus 6 months"
ExpiresByType image/jpeg "access plus 6 months" ExpiresByType image/png "access plus 6 months" ExpiresByType text/css "access plus 6 months" ExpiresByType text/javascript "access plus 6 months"
gzip #3
.htaccess #3 AddOutputFilterByType DEFLATE text/html AddOutputFilterByType DEFLATE text/plain AddOutputFilterByType DEFLATE
text/xml AddOutputFilterByType DEFLATE text/css AddOutputFilterByType DEFLATE application/javascript
bonus ^
ferramentas de análise #2
http://yslow.org/
https://developers.google.com/speed/pagespeed/insights_extensions?hl=pt-BR
http://www.webpagetest.org/
performance deve ser pensada no projeto como um todo
e não só deixar pra testar no finalzinho
lembre-se
o preguiçoso trabalha dobrado
quero aprender mais, aonde eu vou?
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https://developers.google.com/speed/docs/best-practices/rules_intro
http://developer.yahoo.com/performance/rules.html
nada em português?
e se a gente juntasse...
renato mangini - google
sérgio lopes - caelum
mike taylor - opera
marcel duran - twitter
“Pica voando das galáxias criado em cativeiro” browserdiet.com/pt
“Pica voando das galáxias criado em cativeiro” - Bernard de
Luna
“Pica voando das galáxias criado em cativeiro” - Bernard de
Luna
2º Encontro - 2011
fim. zenorocha.com browserdiet.com #1