From 074785cea106179cb3305637055ab0a009ca74f2 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Tue, 8 Dec 2020 14:42:52 -0500 Subject: initial commit --- files/pt-br/web/api/performance/now/index.html | 160 +++++++++++++++++++++++++ 1 file changed, 160 insertions(+) create mode 100644 files/pt-br/web/api/performance/now/index.html (limited to 'files/pt-br/web/api/performance/now/index.html') diff --git a/files/pt-br/web/api/performance/now/index.html b/files/pt-br/web/api/performance/now/index.html new file mode 100644 index 0000000000..b6539ebebe --- /dev/null +++ b/files/pt-br/web/api/performance/now/index.html @@ -0,0 +1,160 @@ +--- +title: performance.now() +slug: Web/API/Performance/now +translation_of: Web/API/Performance/now +--- +
{{APIRef("High Resolution Timing")}}
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O método performance.now() retorna {{domxref("DOMHighResTimeStamp")}}, medido em milisegundos, com precisão de cinco milésimos de milissegundo (5 microsegundos).

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O valor retornado representa o tempo decorrido desde o time origin (the {{domxref("PerformanceTiming.navigationStart")}} property). Em um web worker, o tempo inicial é o momento em que o contexto da execução(e.g. thread ou processo) é criado. Em uma janela, é o tempo em que o usuário iniciou a navegação neste documento. Tenha em mente que:

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Sintaxe

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t = performance.now();
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Exemplo

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var t0 = performance.now();
+doSomething();
+var t1 = performance.now();
+console.log("Call to doSomething took " + (t1 - t0) + " milliseconds.");
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Unlike other timing data available to JavaScript (for example Date.now), the timestamps returned by Performance.now() are not limited to one-millisecond resolution. Instead, they represent times as floating-point numbers with up to microsecond precision.

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Also unlike Date.now(), the values returned by Performance.now() always increase at a constant rate, independent of the system clock (which might be adjusted manually or skewed by software like NTP). Otherwise, performance.timing.navigationStart + performance.now() will be approximately equal to Date.now().

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Especificações

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SpecificationStatusComment
{{SpecName('Highres Time Level 2', '#dom-performance-now', 'performance.now()')}}{{Spec2('Highres Time Level 2')}}Stricter definitions of interfaces and types.
{{SpecName('Highres Time', '#dom-performance-now', 'performance.now()')}}{{Spec2('Highres Time')}}Initial definition
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Compatibilidade de Navegadores

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{{CompatibilityTable}}

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FeatureChromeEdgeFirefox (Gecko)Internet ExplorerOperaSafari
Basic support{{CompatChrome("20.0")}} {{property_prefix("webkit")}}
+ {{CompatChrome("24.0")}} [1]		{{CompatVersionUnknown}}{{CompatGeckoDesktop("15.0")}}10.0{{CompatOpera("15.0")}}{{CompatSafari("8.0")}}
on Web workers{{CompatChrome("33")}}{{CompatUnknown}}{{CompatGeckoDesktop("34.0")}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}
now() in a dedicated worker is now separate from the main context's now().{{CompatUnknown}}{{CompatUnknown}}{{CompatGeckoDesktop("45.0")}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}
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FeatureAndroidAndroid WebviewEdgeFirefox Mobile (Gecko)IE MobileOpera MobileSafari MobileChrome for Android
Basic support{{CompatAndroid("4.0")}}{{CompatChrome("25.0")}}{{CompatVersionUnknown}}{{CompatGeckoMobile("15.0")}}10.0{{CompatNo}}9{{CompatChrome("25.0")}}
on Web workers{{CompatUnknown}}{{CompatVersionUnknown}}{{CompatUnknown}}{{CompatGeckoMobile("34.0")}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}{{CompatVersionUnknown}}
now() in a dedicated worker is now separate from the main context's now().{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}{{CompatGeckoMobile("45.0")}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}{{CompatUnknown}}
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[1] Windows versions of Chrome 20 through 33 return performance.now() only to millisecond precision.

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Veja também

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