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<pre class="prettyprint lang-js">/*!
* Ext JS Library 3.4.0
* Copyright(c) 2006-2011 Sencha Inc.
* licensing@sencha.com
* http://www.sencha.com/license
*/
<div id="cls-Ext.util.DelayedTask"></div>/**
* @class Ext.util.DelayedTask
* <p> The DelayedTask class provides a convenient way to "buffer" the execution of a method,
* performing setTimeout where a new timeout cancels the old timeout. When called, the
* task will wait the specified time period before executing. If durng that time period,
* the task is called again, the original call will be cancelled. This continues so that
* the function is only called a single time for each iteration.</p>
* <p>This method is especially useful for things like detecting whether a user has finished
* typing in a text field. An example would be performing validation on a keypress. You can
* use this class to buffer the keypress events for a certain number of milliseconds, and
* perform only if they stop for that amount of time. Usage:</p><pre><code>
var task = new Ext.util.DelayedTask(function(){
alert(Ext.getDom('myInputField').value.length);
});
// Wait 500ms before calling our function. If the user presses another key
// during that 500ms, it will be cancelled and we'll wait another 500ms.
Ext.get('myInputField').on('keypress', function(){
task.{@link #delay}(500);
});
* </code></pre>
* <p>Note that we are using a DelayedTask here to illustrate a point. The configuration
* option <tt>buffer</tt> for {@link Ext.util.Observable#addListener addListener/on} will
* also setup a delayed task for you to buffer events.</p>
* @constructor The parameters to this constructor serve as defaults and are not required.
* @param {Function} fn (optional) The default function to call.
* @param {Object} scope The default scope (The <code><b>this</b></code> reference) in which the
* function is called. If not specified, <code>this</code> will refer to the browser window.
* @param {Array} args (optional) The default Array of arguments.
*/
Ext.util.DelayedTask = function(fn, scope, args){
var me = this,
id,
call = function(){
clearInterval(id);
id = null;
fn.apply(scope, args || []);
};
<div id="method-Ext.util.DelayedTask-delay"></div>/**
* Cancels any pending timeout and queues a new one
* @param {Number} delay The milliseconds to delay
* @param {Function} newFn (optional) Overrides function passed to constructor
* @param {Object} newScope (optional) Overrides scope passed to constructor. Remember that if no scope
* is specified, <code>this</code> will refer to the browser window.
* @param {Array} newArgs (optional) Overrides args passed to constructor
*/
me.delay = function(delay, newFn, newScope, newArgs){
me.cancel();
fn = newFn || fn;
scope = newScope || scope;
args = newArgs || args;
id = setInterval(call, delay);
};
<div id="method-Ext.util.DelayedTask-cancel"></div>/**
* Cancel the last queued timeout
*/
me.cancel = function(){
if(id){
clearInterval(id);
id = null;
}
};
};</pre>
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