How Do I Get a Unix Timestamp (or Milliseconds Since Epoch) in JavaScript?

How to Obtain Timestamp in JavaScript

To obtain a representation of the current date and time as a single numerical value, similar to a Unix timestamp, JavaScript provides several methods.

Timestamp in Milliseconds:

To retrieve the number of milliseconds since the Unix epoch, use Date.now():

Date.now();

Alternatively, for compatibility with older browsers, you can use the following:

+new Date();

Timestamp in Seconds (Unix Timestamp):

To obtain the number of seconds since the Unix epoch, commonly known as the Unix timestamp, calculate the quotient of Date.now() divided by 1000:

Math.floor(Date.now() / 1000);

Higher Resolution Timestamp in Milliseconds:

For a higher resolution timestamp in milliseconds, use performance.now():

var isPerformanceSupported = (
    window.performance &&
    window.performance.now &&
    window.performance.timing &&
    window.performance.timing.navigationStart
);

var timeStampInMs = (
    isPerformanceSupported ?
    window.performance.now() +
    window.performance.timing.navigationStart :
    Date.now()
);

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