dojo.when

Status:Draft Version:1.0 Available:since V1.5

Contents

• dojo.when
  • Usage
  • See Also

dojo.when provides the ability to define a callback (and error handler) for the eventual completion of a Deferred or promise object, or any standard synchronous value.

Usage

The first argument to the dojo.when may be any value, the second argument is the callback, and the optional third argument is the error callback. If the first argument is a promise (like a dojo.Deferred object), then the callback (or error callback) will be called when the promise is resolved. If the first argument is not a promise, the callback will be call immediately (with the value passed as the first argument.

Example 1: Creating and calling a deferred.

<script type="text/javascript">
  dojo.when(4, print); // this will print 4

  var fourAsync = dojo.Deferred();
  dojo.when(fourAsync, print); // this will print 4, one second later when the Deferred is resolved
  setTimeout(function(){
    fourAsync.callback(4);
  }, 1000);

  function print(value){
    console.log(value);
  }
</script>

See Also

• dojo.Deferred()
• Article on the new design of Deferreds in 1.5: http://www.sitepen.com/blog/2010/05/03/robust-promises-with-dojo-deferred-1-5/

Table of Contents

• dojo.when
  • Usage
    • Example 1: Creating and calling a deferred.
  • See Also