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paulirish / performance.now()-polyfill.js
Last active August 1, 2023 15:42
performance.now() polyfill (aka perf.now())
// @license http://opensource.org/licenses/MIT
// copyright Paul Irish 2015
// Date.now() is supported everywhere except IE8. For IE8 we use the Date.now polyfill
// github.com/Financial-Times/polyfill-service/blob/master/polyfills/Date.now/polyfill.js
// as Safari 6 doesn't have support for NavigationTiming, we use a Date.now() timestamp for relative values
// if you want values similar to what you'd get with real perf.now, place this towards the head of the page
// but in reality, you're just getting the delta between now() calls, so it's not terribly important where it's placed