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javascripttimeperformance.now

performance.now() vs Date.now()

What is the difference between performance.now() and Date.now()?

Should I consider performance.now() as a replacement for Date.now() since performace.now() is more consistent and independent?

Solution

  • They both serve different purposes.

    performance.now() is relative to page load and more precise in orders of magnitude. Use cases include benchmarking and other cases where a high-resolution time is required such as media (gaming, audio, video, etc.)

    It should be noted that performance.now() is only available in newer browsers (including IE10+).

    Date.now() is relative to the Unix epoch (1970-01-01T00:00:00Z) and dependent on system clock. Use cases include same old date manipulation ever since the beginning of JavaScript.

    See When milliseconds are not enough: performance.now and now method (Internet Explorer) - MSDN for more information.

    The official W3C spec can be found here: High Resolution Time API