{"id":23,"date":"2016-02-23T02:18:23","date_gmt":"2016-02-23T02:18:23","guid":{"rendered":"http:\/\/www.onux.com\/jspp\/blog\/?p=23"},"modified":"2016-06-06T03:32:17","modified_gmt":"2016-06-06T03:32:17","slug":"design-notes-void-and-undefined","status":"publish","type":"post","link":"https:\/\/www.onux.com\/jspp\/blog\/design-notes-void-and-undefined\/","title":{"rendered":"Design Notes: void and undefined"},"content":{"rendered":"

JS++ replaces the “void” keyword as a type annotation rather than being like JavaScript which dictates that “void” is a keyword used to evaluate an expression and always returns undefined. This doesn’t serve much practical purpose.\u00a0You can accomplish the same effect in many other ways:<\/p>\n

\r\n\/\/ Original\r\nvar a = void foo();\r\n\r\n\/\/ Equivalent to:\r\nvar b = (foo(), undefined);\r\nvar c = (function(){ foo(); })();\r\n\/\/ ... etc\r\n<\/pre>\n
Furthermore, “void” is very rarely used in real-world JavaScript. This is why I always say it takes an experienced JavaScript programmer to design a JavaScript superset. It takes someone with deep experience in JavaScript to identify this in order to make such a breaking change with confidence. If you’re introducing a breaking change, make sure it’s just breaking the 1% and not the 99%.<\/p>\n
The enlightened few will use void 0<\/code> in place of undefined<\/code> because the ECMAScript 3 standard defines undefined<\/code> as a global property that can be defined<\/em>!<\/p>\n
JS++, on the other hand, makes undefined<\/code> a keyword. void<\/code> is then used as a type which represents both null<\/code> and undefined<\/code>.<\/p>\n
Finally, there have been informal plans for a JS to JS++ translator. This will handle those few instances where void 0<\/code> is used to mean undefined<\/code> and such. These cases are easy to parse and identify, and it makes introducing such a breaking change fathomable.<\/p>\n","protected":false},"excerpt":{"rendered":"
JS++ replaces the “void” keyword as a type annotation rather than being like JavaScript which dictates that “void” is a keyword used to evaluate an expression and always returns undefined. This doesn’t serve much practical purpose.\u00a0You can accomplish the same effect in many other ways: \/\/ Original var a = void foo(); \/\/ Equivalent to: … Continue reading “Design Notes: void and undefined”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[3],"tags":[],"_links":{"self":[{"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/posts\/23"}],"collection":[{"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/comments?post=23"}],"version-history":[{"count":4,"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/posts\/23\/revisions"}],"predecessor-version":[{"id":52,"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/posts\/23\/revisions\/52"}],"wp:attachment":[{"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/media?parent=23"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/categories?post=23"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.onux.com\/jspp\/blog\/wp-json\/wp\/v2\/tags?post=23"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}