3 * Copyright(c) 2006-2010 Ext JS, Inc.
5 * http://www.extjs.com/license
8 * @class Ext.util.DelayedTask
9 * <p> The DelayedTask class provides a convenient way to "buffer" the execution of a method,
10 * performing setTimeout where a new timeout cancels the old timeout. When called, the
11 * task will wait the specified time period before executing. If durng that time period,
12 * the task is called again, the original call will be cancelled. This continues so that
13 * the function is only called a single time for each iteration.</p>
14 * <p>This method is especially useful for things like detecting whether a user has finished
15 * typing in a text field. An example would be performing validation on a keypress. You can
16 * use this class to buffer the keypress events for a certain number of milliseconds, and
17 * perform only if they stop for that amount of time. Usage:</p><pre><code>
18 var task = new Ext.util.DelayedTask(function(){
19 alert(Ext.getDom('myInputField').value.length);
21 // Wait 500ms before calling our function. If the user presses another key
22 // during that 500ms, it will be cancelled and we'll wait another 500ms.
23 Ext.get('myInputField').on('keypress', function(){
24 task.{@link #delay}(500);
27 * <p>Note that we are using a DelayedTask here to illustrate a point. The configuration
28 * option <tt>buffer</tt> for {@link Ext.util.Observable#addListener addListener/on} will
29 * also setup a delayed task for you to buffer events.</p>
30 * @constructor The parameters to this constructor serve as defaults and are not required.
31 * @param {Function} fn (optional) The default function to call.
32 * @param {Object} scope The default scope (The <code><b>this</b></code> reference) in which the
33 * function is called. If not specified, <code>this</code> will refer to the browser window.
34 * @param {Array} args (optional) The default Array of arguments.
36 Ext.util.DelayedTask = function(fn, scope, args){
42 fn.apply(scope, args || []);
46 * Cancels any pending timeout and queues a new one
47 * @param {Number} delay The milliseconds to delay
48 * @param {Function} newFn (optional) Overrides function passed to constructor
49 * @param {Object} newScope (optional) Overrides scope passed to constructor. Remember that if no scope
50 * is specified, <code>this</code> will refer to the browser window.
51 * @param {Array} newArgs (optional) Overrides args passed to constructor
53 me.delay = function(delay, newFn, newScope, newArgs){
56 scope = newScope || scope;
57 args = newArgs || args;
58 id = setInterval(call, delay);
62 * Cancel the last queued timeout
64 me.cancel = function(){