- From: Ben Rimmington <benrimmington@me.com>
- Date: Sun, 27 Feb 2011 10:53:16 +0000
> 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).
> 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 02:53:16 UTC