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performance em jQuery apps

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  • DOWNLOAD THAT BOOKS INTO AVAILABLE FORMAT (2019 Update) ......................................................................................................................... ......................................................................................................................... Download Full PDF EBOOK here { http://bit.ly/2m6jJ5M } ......................................................................................................................... Download Full EPUB Ebook here { http://bit.ly/2m6jJ5M } ......................................................................................................................... Download Full doc Ebook here { http://bit.ly/2m6jJ5M } ......................................................................................................................... Download PDF EBOOK here { http://bit.ly/2m6jJ5M } ......................................................................................................................... Download EPUB Ebook here { http://bit.ly/2m6jJ5M } ......................................................................................................................... Download doc Ebook here { http://bit.ly/2m6jJ5M } ......................................................................................................................... ......................................................................................................................... ................................................................................................................................... eBook is an electronic version of a traditional print book that can be read by using a personal computer or by using an eBook reader. (An eBook reader can be a software application for use on a computer such as Microsoft's free Reader application, or a book-sized computer that is used solely as a reading device such as Nuvomedia's Rocket eBook.) Users can purchase an eBook on diskette or CD, but the most popular method of getting an eBook is to purchase a downloadable file of the eBook (or other reading material) from a Web site (such as Barnes and Noble) to be read from the user's computer or reading device. Generally, an eBook can be downloaded in five minutes or less ......................................................................................................................... .............. Browse by Genre Available eBooks .............................................................................................................................. Art, Biography, Business, Chick Lit, Children's, Christian, Classics, Comics, Contemporary, Cookbooks, Manga, Memoir, Music, Mystery, Non Fiction, Paranormal, Philosophy, Poetry, Psychology, Religion, Romance, Science, Science Fiction, Self Help, Suspense, Spirituality, Sports, Thriller, Travel, Young Adult, Crime, Ebooks, Fantasy, Fiction, Graphic Novels, Historical Fiction, History, Horror, Humor And Comedy, ......................................................................................................................... ......................................................................................................................... .....BEST SELLER FOR EBOOK RECOMMEND............................................................. ......................................................................................................................... Blowout: Corrupted Democracy, Rogue State Russia, and the Richest, Most Destructive Industry on Earth,-- The Ride of a Lifetime: Lessons Learned from 15 Years as CEO of the Walt Disney Company,-- Call Sign Chaos: Learning to Lead,-- StrengthsFinder 2.0,-- Stillness Is the Key,-- She Said: Breaking the Sexual Harassment Story That Helped Ignite a Movement,-- Atomic Habits: An Easy & Proven Way to Build Good Habits & Break Bad Ones,-- Everything Is Figureoutable,-- What It Takes: Lessons in the Pursuit of Excellence,-- Rich Dad Poor Dad: What the Rich Teach Their Kids About Money That the Poor and Middle Class Do Not!,-- The Total Money Makeover: Classic Edition: A Proven Plan for Financial Fitness,-- Shut Up and Listen!: Hard Business Truths that Will Help You Succeed, ......................................................................................................................... .........................................................................................................................
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performance em jQuery apps

  1. 1. performance em jQuery apps por davidson fellipe
  2. 2. sobre mim• HTML ~ 2001• eletrônica ✓ engenharia da computação ✓• recife ✈ frontend engineer na globo.com• mestrando em informática na puc-rio
  3. 3. ★ regional conferences leader★ rio.js★ pernambuco.js★ front in maceió★ front in bhwww.braziljs.org
  4. 4. atualmente...
  5. 5. por que melhorar a performance?
  6. 6. site demorando...
  7. 7. redução de bytesredução de requestsreduzir o tempo de first view da páginareduzir o trabalho que o browser tem de fazerredução do consumo de memória
  8. 8. não use jQuery, aomenos que ele seja necessário
  9. 9. ...pois alguns métodospodem ser mais fáceis do que você imagina size: function() {return this.length;}
  10. 10. jsPerf• testes comparativos de trechos de códigos• fácil de compartilhar• browsers diferentes• usado pelo jQuery Team,Yahoo e outros
  11. 11. por que usar a última versão?
  12. 12. por que?• otimização de algoritmos• novas funcionalidades• migração é normalmente tranquila
  13. 13. como descobrir a versão?• jQuery.fn.jquery
  14. 14. um problema por usar versão antiga...
  15. 15. um problema por usar versão antiga...
  16. 16. operações por segundo
  17. 17. operações por segundo
  18. 18. teste! teste! teste! antes de fazer a migração
  19. 19. ...mas evite linkar para última versão<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js"></script>
  20. 20. combine, minifique egzipping seus scripts
  21. 21. Tente compactar todos os script em apenas 1 arquivoYUI CompressorMuitos browsers não estão aptos a processar mais que 1 script paralelamente
  22. 22. seletores
  23. 23. DOM é muito lenta!
  24. 24. it’s the part of a CSS rule that matches a set of elements inan HTML or XML document. http://reference.sitepoint.com/css/selectorref
  25. 25. anatomia de um seletorelemento#id.class[attr]:hover > a::after, div + strong http://www.slideshare.net/fabiomirandacosta/otimizao-de-seletores
  26. 26. sizzle: div p• busca todos elementos p • para cada p • verifica se o pai é uma div • se for salva o elemento • se estiver no topo da DOM remove o elemento • senão busca o pai do pai
  27. 27. comparativo entreperformance de seletores
  28. 28. comparativo entreperformance de seletores
  29. 29. evite o seletor universal $(“.box > *”) $(“.box”).children()
  30. 30. evite o seletor universal implicito$(“.box :radio”)$(“.box *:radio”)$(“.box input:radio”)
  31. 31. use cache fellipe.com/slides/jqueryfn
  32. 32. var $materias = $(".materias");for(var i = 0; i < $materias.length; i++){ $materias[i].find(".titulo").html( i );}
  33. 33. Use contexto em seus seletores
  34. 34. http://jsperf.com/ns-jq-cached
  35. 35. http://jsperf.com/ns-jq-cached
  36. 36. formas de seleção1) $parent.find(“.child”).show(); //+ rapida2) $(“.child”, $parent).show(); //~5-10% + lenta3) $(“.child”, $(“#parent”)).show(); //~23% + lenta4) $parent.children(“.child”).show(); //~50% + lenta5) $(“#parent > .child”).show(); //~70% + lenta6) $(“#parent .child”).show(); //~77% + lenta7) $(“#parent span”).show(); //nem pense nisso!http://jsperf.com/jquery-selectors-context/2
  37. 37. $parent.find(“.child”).show();busca usando metodos nativos no $parent em cache.
  38. 38. $(“.child”, $parent).show();a instrução é convertida para $parent.find(“.child”).show();
  39. 39. $(“.child”, $(“#parent”).show();a instrução é convertida para$(“#parent”).find(“.child”).show();
  40. 40. $parent.children(“.child”).show();usa sibling e nextsibling para encontrar outros nós
  41. 41. $(“#parent > .child”).show();$(“#parent .child”).show();$(“#parent span”).show();utilizam a regra da direita para esquerda
  42. 42. console.timeconsole.timeEnd
  43. 43. use encadeamento (chaining)
  44. 44. http://jsperf.com/jquery-chaining
  45. 45. Use For ao invés de Each
  46. 46. http://jsperf.com/jquery-each-vs-for-loop/24
  47. 47. Use id ao invés de classes
  48. 48. jQuery não é uma caixa preta! http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.js
  49. 49. performance x legibilidade
  50. 50. obrigado!• @davidsonfellipe• www.fellipe.com• github.com/davidsonfellipe• www.slideshare.net/davidsonfellipe

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