Echo Web Framework

The Core.Web.Scheduler namespace provides capabilities for scheduling tasks to run after a certain amount of time, or simply in a different JavaScript execution context. It does this by providing an object-oriented wrapper around the Window object's setTimeout() method.

The Scheduler namespace provides an abstract Runnable class which is used to define a task to be executed. Runnable implementations must provide a run() method which will be invoked by the scheduler to perform the task when appropriate. Implementations may optionally define a timeInterval property to specify the number of milliseconds after which the task should be executed, and a repeat boolean flag which may be set to cause execution to repeated at that interval. If the timeInterval property is not specified, the task will be executed immediately, but in a new JavaScript execution context.

A Runnable can be scheduled for execution by passing it to the Core.Web.Scheduler.add() method. Likewise, one can be canceled from future execution by passing it to the Core.Web.Scheduler.remove() method.

An Example

The following code defines a Runnable implementation which raises an alert dialog after 5 seconds. An instance of the runnable is then created and scheduled:

DelayedMessageRunnable = Core.extend(Core.Web.Scheduler.Runnable, {

    _message: null,

    $construct: function(message) {
        this._message = message;
    },

    timeInterval: 5000,

    run: function() {
        alert("Delayed message: " + this._message);
    }
});

Core.Web.Scheduler.add(new DelayedMessageRunnable("Foo!"));

Convenience Features

The namespace also provides several shorthands for scheduling code to be executed. The Core.Web.Scheduler.run() method can be used to create a Runnable and execute it immediately. The Core.Web.Scheduler.MethodRunnable object provides a concrete implementation of Runnable to simply execute a specific function or method.

The following example shows the use of Core.Web.Scheduler.run():

Core.Web.Scheduler.run(function() { alert("Foo!"); }, 5000, false);