fnNow = function now() {
		return performance.timeOrigin + performance.now();
	}
Returns a high resolution timestamp in microseconds.
The timestamp is based on 01/01/1970 00:00:00 (UNIX epoch) as float with microsecond precision.
The fractional part of the timestamp represents fractions of a millisecond.
Converting to a <code>Date</code> is possible by using <code>require(["sap/base/util/now"], function(now){new Date(now());}</code>

@function
@since 1.58
@public
@alias module:sap/base/util/now
@returns {float} timestamp in microseconds