From 7953e984bdc905a349532d40a210cdaea88910e0 Mon Sep 17 00:00:00 2001 From: Michael Ficarra Date: Tue, 30 Aug 2022 19:34:31 -0600 Subject: [PATCH] more phrasing --- spec.html | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/spec.html b/spec.html index 2e48be0dfb..d62eaa085a 100644 --- a/spec.html +++ b/spec.html @@ -32051,7 +32051,7 @@

Overview of Date Objects and Definitions of Abstract Operations

Time Values and Time Range

Time measurement in ECMAScript is analogous to time measurement in POSIX, in particular sharing definition in terms of the proleptic Gregorian calendar, an epoch of midnight at the beginning of 1 January 1970 UTC, and an accounting of every day as comprising exactly 86,400 seconds (each of which is 1000 milliseconds long).

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An ECMAScript time value is a Number, either a finite integral Number representing an instant in time to millisecond precision or *NaN* representing no specific instant. A time value that is a multiple of 24 × 60 × 60 × 1000 = 86,400,000 (i.e., is equal to 86,400,000 × _d_ for some integer _d_) represents the instant at the start of the UTC day that follows the epoch by _d_ whole UTC days (preceding the epoch for negative _d_). Every other finite time value _t_ is defined relative to the greatest preceding time value _s_ that is such a multiple, and represents the instant that occurs within the same UTC day as _s_ but follows it by (_t_ - _s_) milliseconds.

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An ECMAScript time value is a Number, either a finite integral Number representing an instant in time to millisecond precision or *NaN* representing no specific instant. A time value that is a multiple of 24 × 60 × 60 × 1000 = 86,400,000 (i.e., is 86,400,000 × _d_ for some integer _d_) represents the instant at the start of the UTC day that follows the epoch by _d_ whole UTC days (preceding the epoch for negative _d_). Every other finite time value _t_ is defined relative to the greatest preceding time value _s_ that is such a multiple, and represents the instant that occurs within the same UTC day as _s_ but follows it by (_t_ - _s_) milliseconds.

Time values do not account for UTC leap seconds—there are no time values representing instants within positive leap seconds, and there are time values representing instants removed from the UTC timeline by negative leap seconds. However, the definition of time values nonetheless yields piecewise alignment with UTC, with discontinuities only at leap second boundaries and zero difference outside of leap seconds.

A Number can exactly represent all integers from -9,007,199,254,740,992 to 9,007,199,254,740,992 ( and ). A time value supports a slightly smaller range of -8,640,000,000,000,000 to 8,640,000,000,000,000 milliseconds. This yields a supported time value range of exactly -100,000,000 days to 100,000,000 days relative to midnight at the beginning of 1 January 1970 UTC.

The exact moment of midnight at the beginning of 1 January 1970 UTC is represented by the time value *+0*𝔽.