HTTP/2 200
content-type: text/html
x-guploader-uploadid: AAwnv3JymcA2FP5VW0H1Hqlo721vOPQ1J7rUM84Msxvf0nAIFAQKHDIE5zq28mo49s_TSwXF
cache-control: public, max-age=3600
expires: Fri, 10 Oct 2025 08:27:16 GMT
last-modified: Fri, 10 Oct 2025 01:10:37 GMT
etag: W/"4aa3ff5e55333530dbd05d576b3c2364"
x-goog-generation: 1760058637729545
x-goog-metageneration: 1
x-goog-stored-content-encoding: identity
x-goog-stored-content-length: 154001
x-goog-meta-goog-reserved-file-mtime: 1760056908
x-goog-hash: crc32c=MdLKgw==, md5=SqP/XlUzNTDb0F1XazwjZA==
x-goog-storage-class: STANDARD
accept-ranges: none
alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
alt-svc: clear
referrer-policy: strict-origin-when-cross-origin
x-content-type-options: nosniff
strict-transport-security: max-age=63072000
content-security-policy: default-src 'self'; script-src 'report-sample' 'self' 'wasm-unsafe-eval' https://www.google-analytics.com/analytics.js https://www.googletagmanager.com/gtag/js assets.codepen.io production-assets.codepen.io https://js.stripe.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; script-src-elem 'report-sample' 'self' 'wasm-unsafe-eval' https://www.google-analytics.com/analytics.js https://www.googletagmanager.com/gtag/js assets.codepen.io production-assets.codepen.io https://js.stripe.com 'sha256-XNBp89FG76amD8BqrJzyflxOF9PaWPqPqvJfKZPCv7M=' 'sha256-YCNoU9DNiinACbd8n6UPyB/8vj0kXvhkOni9/06SuYw=' 'sha256-PZjP7OR6mBEtnvXIZfCZ5PuOlxoDF1LDZL8aj8c42rw='; style-src 'report-sample' 'self' 'unsafe-inline'; object-src 'none'; base-uri 'self'; connect-src 'self' developer.allizom.org bcd.developer.allizom.org bcd.developer.mozilla.org updates.developer.allizom.org updates.developer.mozilla.org https://*.google-analytics.com https://*.analytics.google.com https://*.googletagmanager.com https://incoming.telemetry.mozilla.org https://observatory-api.mdn.allizom.net https://observatory-api.mdn.mozilla.net https://api.github.com/search/issues stats.g.doubleclick.net https://api.stripe.com; font-src 'self'; frame-src 'self' interactive-examples.mdn.mozilla.net interactive-examples.mdn.allizom.net mdn.github.io live-samples.mdn.mozilla.net live-samples.mdn.allizom.net *.mdnplay.dev *.mdnyalp.dev *.play.test.mdn.allizom.net https://v2.scrimba.com https://scrimba.com jsfiddle.net www.youtube-nocookie.com codepen.io survey.alchemer.com https://js.stripe.com; img-src 'self' data: *.githubusercontent.com *.googleusercontent.com *.gravatar.com mozillausercontent.com firefoxusercontent.com profile.stage.mozaws.net profile.accounts.firefox.com developer.mozilla.org mdn.dev interactive-examples.mdn.mozilla.net interactive-examples.mdn.allizom.net wikipedia.org upload.wikimedia.org https://mdn.github.io/shared-assets/ https://mdn.dev/ https://*.google-analytics.com https://*.googletagmanager.com www.gstatic.com; manifest-src 'self'; media-src 'self' archive.org videos.cdn.mozilla.net https://mdn.github.io/shared-assets/; child-src 'self'; worker-src 'self';
x-frame-options: DENY
origin-trial: AxVILwizhbMjxFeHOn1P3R8niO1RJY/smaK4B4d1rLzc1gTaxtXMSaTi+FoigYgCw40uFRDwFcEAeqDR+vVLOW4AAABfeyJvcmlnaW4iOiJodHRwczovL2RldmVsb3Blci5tb3ppbGxhLm9yZyIsImZlYXR1cmUiOiJQcml2YXRlQXR0cmlidXRpb25WMiIsImV4cGlyeSI6MTc0MjA3OTYwMH0=
x-cloud-trace-context: cf44c663a59a053f052ab4789a55cc4b
date: Fri, 10 Oct 2025 07:27:16 GMT
server: Google Frontend
via: 1.1 google
vary: Accept-Encoding
content-encoding: gzip
x-cache: miss
AnimationPlaybackEvent: currentTime プロパティ - Web API | MDN
ミリ秒単位の現在時刻を表す数値、または null
です。
タイミング攻撃やフィンガープリンティングから保護するために、 animation.currentTime
の精度はブラウザー設定によっては丸められている可能性があります。
Firefox では、 privacy.reduceTimerPrecision
環境設定が既定で有効になっており、 Firefox 59 では 20 マイクロ秒が既定値です。
// Firefox 60 における 時間制度の低下 (2ms)
animation.currentTime;
// 23.404
// 24.192
// 25.514
// …
// `privacy.resistFingerprinting` が有効な場合の時間制度の低下
animation.currentTime;
// 49.8
// 50.6
// 51.7
// …
Firefox では、 privacy.resistFingerprinting
を有効にすると、精度を 100ms または privacy.resistFingerprinting.reduceTimerPrecision.microseconds
の値のどちらか大きい方にすることができます。