Because we have no desire to differentiate between undefined & null. David
On Sun, Aug 17, 2014 at 8:49 AM, Angel Java Lopez <[email protected]> wrote: > Just curious > > Why then > > is-hidden != null > > instead of > > is-hidden !== null > > Angel "Java" Lopez > @ajlopez > > > On Sun, Aug 17, 2014 at 9:45 AM, stephanos <[email protected]> wrote: >> >> Thank you! It make sense now :) >> >> >> On Sunday, August 17, 2014 2:44:23 PM UTC+2, [email protected] wrote: >> > The boolean metadata is a type hint telling the ClojureScript compiler >> > that is-hidden is boolean. Knowing is-hidden is a boolean allows >> > ClojureScript to compile to >> > >> > if (is-hidden){ >> > } >> > else { >> > } >> > >> > instead of >> > >> > if (is-hidden != null && is-hidden !== false){ >> > } >> > else { >> > } >> > >> > if the type isn't known to be a boolean. The extra checks are needed >> > because ClojureScript has only two values that evaluate to false: false and >> > nil. JavaScript evaluates false, null undefined, "", 0, and NaN to be >> > false. >> > >> > About the only time you need to use the boolean type hint is in >> > performance sensitive code where the compiler can't infer the type of a var >> > (like a parameter passed into a function). >> > >> > I hope this answers your question >> > >> > Peter Schuck >> >> -- >> Note that posts from new members are moderated - please be patient with >> your first post. >> --- >> You received this message because you are subscribed to the Google Groups >> "ClojureScript" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/clojurescript. > > > -- > Note that posts from new members are moderated - please be patient with your > first post. > --- > You received this message because you are subscribed to the Google Groups > "ClojureScript" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/clojurescript. -- Note that posts from new members are moderated - please be patient with your first post. --- You received this message because you are subscribed to the Google Groups "ClojureScript" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/clojurescript.
