単純なマッチで複数回replaceするのと、文字クラスを使って一回replaceするのでは、どちらが速いか - anti scroll
qiitaでこんな記事がありました。 innerText(textContent)/innerHTMLを使わずJavaScriptでHTMLエスケープ - Qiita で、思い出したのですが「文字クラスでreplaceを一度で済ますより、単純なマッチを直列で繰り返したほうが速い」って話しをどこかで聞いた覚えがあるので、どのぐらい差があるのか、ちょっと試してみました。 念のため、元記事の関数でテーブル参照をしないバージョン（escapeCharClassEx）も用意。 3パターンのescape関数 // 元記事の関数 var escapeCharClass = function(content) { var TABLE_FOR_ESCAPE_HTML = { "&": "&", "\"": """, "<": "<", ">": ">" }; return co
ecmascript generators from a performance perspective — wingolog
It's been really gratifying to see the recent interest in ES6 generators in V8. I'm still a Schemer at heart, but one thing all language communities should learn from JS is its enthusiasm and sense of joyful play. One can't spend much time around folks like James Long or Domenic Denicola without feeling the urge to go out and build something fun. perfie perf perf perf But this is a blog about narg
jQuery 2.0.0 · jsPerf
Revisions You can edit these tests or add even more tests to this page by appending /edit to the URL. Revision 1: published Andreas Goebel on 2011-2-26 Revision 2: published RoVeRT on 2011-2-26 Revision 3: published Mathias Bynens on 2011-3-27 Revision 4: published on 2011-3-27 Revision 6: published on 2011-4-1 Revision 7: published on 2011-4-1 Revision 8: published jess jacobs on 2011-6-1 Revisio
Promises/A+ Performance Hits You Should Be Aware Of
The Promises/A+ specification is a fresh and very interesting way of dealing with the asynchronous nature of Javascript. It also provides a sensible way to deal with error handling and exceptions. In this article we will go through the performance hits you should be aware of and as a side-effect do a comparison between the two most popular Promises/A+ implementations, When and Q and how they compa
"Type of undefined" vs "=== undefined" · jsPerf
JavaScript performance comparison Revision 6 of this test case created by Mihai Bazon on 2012-9-16 Preparation code <script> Benchmark.prototype.setup = function() { var a = 1, b = true, c = "c", d = [], e = {}, u; }; </script> Test runner Warning! For accurate results, please disable Firebug before running the tests. (Why?) Java applet disabled.
JSC Array optimization for adding new property - 枕を欹てて聴く
This is a blog post for 12/6 VM advent calendar. See http://qiita.com/advent-calendar/2012/vm for more nice blog posts :) Introduction ECMA262にとってArrayは最も重要なObjectの1つであり, loop内で高い頻度でアクセスされる性質上, Arrayの最適化はengineの実行速度に多大な影響を及ぼします. ここではJavaScriptCoreの行なっているArrayに対して新しいpropertyを追加する処理の最適化を紹介します. Background ECMA262において, Arrayはliteral形式ならばown propertyを最初から定義できますが, var array = [0, 1, 2, 3, 4]; console.lo
Performance with JavaScript String Objects – Mozilla Hacks - the Web developer blog
This article aims to take a look at the performance of JavaScript engines towards primitive value Strings and Object Strings. It is a showcase of benchmarks related to the excellent article by Kiro Risk, The Wrapper Object. Before proceeding, I would suggest visiting Kiro’s page first as an introduction to this topic. The ECMAScript 5.1 Language Specification (PDF link) states at paragraph 4.3.18
New community features for Google Chat and an update on Currents
Join the official community for Google Workspace administrators In the Google Cloud Community, connect with Googlers and other Google Workspace admins like yourself. Participate in product discussions, check out the Community Articles, and learn tips and tricks that will make your work and life easier. Be the first to know what's happening with Google Workspace. ______________ Learn about more Goo
JavaScript的startsWith — ありえるえりあ
closureのgoog.string.startsWithやprototype.jsのString.startsWithではindexOfを呼ぶコードになってます。 goog.string.startsWith = function(str, prefix) { return str.indexOf(prefix) == 0; }; これだとstrが長い文字列でしかもprefixがstr内になかった場合に無駄な探索処理をやる羽目になります。 代わりに正規表現やsubstringを使って比較をすれば処理速度の悪化は避けられそうですが、正規表現や文字列のオブジェクト生成コストが気になります。 そこでlastIndexOfを使って書けば無駄な探索もオブジェクト生成も避けられるはずです。 str.lastIndexOf(prefix, 0) == 0; もちろんendsWithもindexOfで
13 JavaScript Performance Tips
Daniel Clifford recently gave a great talk at Google I/O 2012 called “Breaking the JavaScript Speed Limit with V8”. In it he goes in depth to explain 13 simple optimizations you can do in your JavaScript code to help Chrome’s V8 JavaScript engine compile / run your JavaScript code faster. In the talk he gives a lot of great explanations as to what they are and why they help, but if you just want t
array.length vs. cached · jsPerf
JavaScript performance comparison Test case created by kazuho on 2012-7-2 Preparation code <script> Benchmark.prototype.setup = function() { var a = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ]; a = a.concat(a, a, a, a, a, a, a, a); }; </script> Test runner Warning! For accurate results, please disable Firebug before running the tests. (Why?) Java applet disabled.
nextSibling vs childNodes · jsPerf
JavaScript performance comparison Test case created by Adrian Sutton on 2010-10-10 Preparation code <div id="container"> <p>Child</p> <p>Child</p> <p>Child</p> <p>Child</p> <p>Child</p> <p>Child</p> <p>Child</p> <p>Child</p> <p>Child</p> <p>Child</p> </div> <script> var container = document.getElementById('container'); function process(element) {} </script> Preparation code output <div id="contain
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