[1]

A number value is a member of the type Number and is a direct representation of a number.

ECMAScript Language Specification (HTML version) ( 版) http://bclary.com/2004/11/07/#a-4.3.19

[2]

The type Number is a set of values representing numbers. In ECMAScript, the set of values represents the double-precision 64-bit format IEEE 754 values including the special “Not-a-Number” (NaN) values, positive infinity, and negative infinity.

ECMAScript Language Specification (HTML version) ( 版) http://bclary.com/2004/11/07/#a-4.3.20

[3]

A Number object is a member of the type Object and is an instance of the built-in Number object. That is, a Number object is created by using the Number constructor in a new expression, supplying a number as an argument. The resulting object has an implicit (unnamed) property that is the number. A Number object can be coerced to a number value by calling the Number constructor as a function (15.7.1).

ECMAScript Language Specification (HTML version) ( 版) http://bclary.com/2004/11/07/#a-4.3.21
[5] Safari 9.0 ( 版) https://developer.apple.com/library/safari/releasenotes/General/WhatsNewInSafari/Articles/Safari_9.html#//apple_ref/doc/uid/TP40014305-CH9-SW27

The following ECMAScript 6 content is now supported by Safari:

Number Object

[6] Write structured clone algorithm in terms of ECMAScript · whatwg/html@bfb960c ( 版) https://github.com/whatwg/html/commit/bfb960c938580c95e77365e614218b952f96375b

[7] Breaking: refactor structured clone into serialize/deserialize (domenic著, ) https://github.com/whatwg/html/commit/97d644c97335956610a31e8ad98d1a388c063e84

[4] Editorial: improve language used around real numeric values. (#388) (tobie著, ) https://github.com/heycam/webidl/commit/79cfa440c3e1e77349640667efdda4feaea637c2

[8] 22888 – 4.2.{14,15}: "has the same numeric value" () https://www.w3.org/Bugs/Public/show_bug.cgi?id=22888

[9] Editorial: improve language used around real numeric values. by tobie · Pull Request #388 · heycam/webidl () https://github.com/heycam/webidl/pull/388