- From: Diego Perini <diego.perini@gmail.com>
- Date: Sun, 27 Feb 2011 20:10:05 +0100
On Sun, Feb 27, 2011 at 11:53 AM, Ben Rimmington <benrimmington at me.com> wrote: >> Feature detection needs to be possible without actually calling the function--without actually opening a prompt. ?For example, if you're to run the above prompt from a timeout, you need to know that *before* you call prompt(), since you don't want a timeout if the async API is supported. > > You'd only need to use window.setTimeout() if window.prompt() ignored your callback argument and didn't return it: > >> function promptWrapper(message, default, callback) { >> ? ? var result = window.prompt(message, default, callback); >> ? ? if (callback && (typeof callback === "function")) { >> ? ? ? ? if (result !== callback) { >> ? ? ? ? ? ? /*** INSTEAD OF: callback(result); ***/ >> ? ? ? ? ? ? window.setTimeout(callback, 1, result); >> ? ? ? ? } >> ? ? ? ? return callback; >> ? ? } >> ? ? return result; >> } > > However, as you pointed out, this "feature detection" only occurs after window.prompt() is invoked. A better way might be to test the window.prompt.length property (if 3 or more then non-blocking mode is supported). > Firefox 3.6.13 already returns 4 for "window.prompt.length". Are the 2 extra parameters already known/used ? -- Diego >> The pattern in new APIs like IDB and FileAPI is to have separate sync and async interfaces, not overloaded behavior, eg: >> >> promptAsync(message, default, callback); >> >> Better off just leaving this crusty old API in the legacy bin, though. > > Agreed. > >
Received on Sunday, 27 February 2011 11:10:05 UTC