How is WinJS.Promise.timeout supposed to be used?

Question

I am currently using

myAsync()

return new WinJS.Promise(function(complete, error, progress) {

  return setTimeout(function() {

     /// work

    complete();

 }

}

How could I convert this to the timout promise that uses setImmediate?

Answer 1

Hi Phil,

This is documented here:

http://msdn.microsoft.com/en-us/library/windows/apps/br229729.aspx

timeout

Type: Int

The timeout period in milliseconds. If this value is zero or not specified                 msSetImmediate is called, otherwise setTimeout is called.

Perhaps I don't understand the question?

-Jeff

---

Jeff Sanders (MSFT)

Answer 2

I read the docs, but I do not understand how to use the function: How would my code above needed to be refactored for WinJS.Promise.timeout?

myAsync()

return WinJS.Promise.timeout(0, function(complete, error, progress) {

     /// work

    complete();

}

But this throws an exception, cause complete is not defined

Answer 3

Hi Phil,

Typically you use timeout when you want a small delay before something happens. So let's say you wanted to wait 5 seconds before taking some action:

WinJS.Promise.timeout(5000).then(function(c) { 
  console.log("Roughly five seconds later...");
});

Of course this could be chained off another promise:

DoSomethingAsync().then(WinJS.Promise.timeout(5000)).then(function(c) { 
  console.log("Roughly five seconds after DoSomething returned...");
});

The second parameter is a little bit different. That's if you wanted to cancel something if it doesn't return fast enough. So, say you wanted to cancel an XHR if it didn't return in 250ms:

WinJS.timeout(250, WinJS.xhr(options).then(updateUI));

Cheers,

-Jeff

Answer 4

WinJS.Promise.timeout(5000).then(function(c) { 
  console.log("Roughly five seconds later...");
});

This could also use the timeout(0) for msImmediate?

Answer 5

Yep, if you specify a length of 0, WinJS will call msSetImmediate instead of setTimeout internally.

Cheers,

-Jeff