{"id":106430,"date":"2022-04-04T07:00:00","date_gmt":"2022-04-04T14:00:00","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/oldnewthing\/?p=106430"},"modified":"2022-04-02T05:31:47","modified_gmt":"2022-04-02T12:31:47","slug":"20220404-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20220404-00\/?p=106430","title":{"rendered":"How are Windows Runtime GUIDs represented in JavaScript?"},"content":{"rendered":"

One of the fundamental data types in the Windows Runtime is the Guid<\/code>. In most languages, it is represented as a binary-formatted data type like System.Guid<\/code> or winrt::guid<\/code>. But JavaScript doesn’t have a corresponding data type. So how are Windows Runtime Guid<\/code>s represented in JavaScript?<\/p>\n

As strings.<\/p>\n

But strings in a special format.<\/p>\n

If a Windows Runtime function accepts a Guid<\/code>, the JavaScript projection accepts a string in one of the following formats:<\/p>\n\n\n\n\n\n\n\n\n
Format<\/th>\nDescription<\/th>\n<\/tr>\n
aaaaaaaabbbbccccddeeffgghhiijjkk<\/code><\/td>\nRaw hex<\/td>\n<\/tr>\n
aaaaaaaa-bbbb-cccc-ddee-ffgghhiijjkk<\/code><\/td>\nHex with dashes<\/td>\n<\/tr>\n
(aaaaaaaa-bbbb-cccc-ddee-ffgghhiijjkk)<\/code><\/td>\nHex with dashes enclosed in parentheses<\/td>\n<\/tr>\n
{aaaaaaaa-bbbb-cccc-ddee-ffgghhiijjkk}<\/code><\/td>\nHex with dashes enclosed in braces<\/td>\n<\/tr>\n
{ 0xaaaaaaaa, 0xbbbb, 0xcccc,
\n{ 0xdd, 0xee, 0xff, 0xgg, 0xhh, 0xii, 0xjj, 0xkk } }<\/code><\/td>\n		C initializer<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Letters a<\/code> through k<\/code> represent any hexadecimal digit. All parsing is case-insensitive. (That includes the x<\/code> in the 0x<\/code> of the C initializer format.)<\/p>\n

In all cases, leading and trailing whitespace are ignored. A whitespace character is one which is classified as whitespace in Unicode version 6.2, which was the latest version of Unicode at the time JavaScript support was implemented.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Character<\/th>\nCode point<\/th>\n<\/tr>\n
CHARACTER TABULATION<\/td>\nU+0009<\/td>\n<\/tr>\n
LINE FEED<\/td>\nU+000A<\/td>\n<\/tr>\n
LINE TABULATION<\/td>\nU+000B<\/td>\n<\/tr>\n
FORM FEED<\/td>\nU+000C<\/td>\n<\/tr>\n
CARRIAGE RETURN<\/td>\nU+000D<\/td>\n<\/tr>\n
SPACE<\/td>\nU+0020<\/td>\n<\/tr>\n
NEXT LINE<\/td>\nU+0085<\/td>\n<\/tr>\n
NO-BREAK SPACE<\/td>\nU+00A0<\/td>\n<\/tr>\n
OGHAM SPACE MARK<\/td>\nU+1680<\/td>\n<\/tr>\n
MONGOLIAN VOWEL SEPARATOR<\/td>\nU+180E<\/td>\n<\/tr>\n
EN QUAD<\/td>\nU+2000<\/td>\n<\/tr>\n
EM QUAD<\/td>\nU+2001<\/td>\n<\/tr>\n
EN SPACE<\/td>\nU+2002<\/td>\n<\/tr>\n
EM SPACE<\/td>\nU+2003<\/td>\n<\/tr>\n
THREE-PER-EM SPACE<\/td>\nU+2004<\/td>\n<\/tr>\n
FOUR-PER-EM SPACE<\/td>\nU+2005<\/td>\n<\/tr>\n
IX-PER-EM SPACE<\/td>\nU+2006<\/td>\n<\/tr>\n
FIGURE SPACE<\/td>\nU+2007<\/td>\n<\/tr>\n
PUNCTUATION SPACE<\/td>\nU+2008<\/td>\n<\/tr>\n
THIN SPACE<\/td>\nU+2009<\/td>\n<\/tr>\n
HAIR SPACE<\/td>\nU+200A<\/td>\n<\/tr>\n
LINE SEPARATOR<\/td>\nU+2028<\/td>\n<\/tr>\n
PARAGRAPH SEPARATOR<\/td>\nU+2029<\/td>\n<\/tr>\n
NARROW NO-BREAK SPACE<\/td>\nU+202F<\/td>\n<\/tr>\n
MEDIUM MATHEMATICAL SPACE<\/td>\nU+205F<\/td>\n<\/tr>\n
IDEOGRAPHIC SPACE<\/td>\nU+3000<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

The MONGOLIAN VOWEL SEPARATOR<\/span> is the odd one out: It was originally classified as whitespace but lost that status in Unicode 6.3.<\/p>\n

Whitespace is permitted in the C initializer format anywhere<\/i>, not just after commas. Strange but true.<\/p>\n

Going the other way is much simpler: If a Windows Runtime function returns a Guid<\/code>, the JavaScript version returns lowercase hex with dashes (no braces or parentheses).<\/p>\n","protected":false},"excerpt":{"rendered":"

They’re strings, in various formats.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[25],"class_list":["post-106430","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"

They’re strings, in various formats.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/106430","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=106430"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/106430\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=106430"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=106430"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=106430"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}