/hippo/src/main/webapp/ext/src/util/core/DelayedTask.js

http://hdbc.googlecode.com/ · JavaScript · 68 lines · 22 code · 2 blank · 44 comment · 5 complexity · 3209a5a50de053e93f905e6e8503ffa0 MD5 · raw file

  1. /*!
  2. * Ext JS Library 3.0.0
  3. * Copyright(c) 2006-2009 Ext JS, LLC
  4. * licensing@extjs.com
  5. * http://www.extjs.com/license
  6. */
  7. /**
  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);
  20. });
  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);
  25. });
  26. * </code></pre>
  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 timeout
  32. * @param {Object} scope (optional) The default scope of that timeout
  33. * @param {Array} args (optional) The default Array of arguments
  34. */
  35. Ext.util.DelayedTask = function(fn, scope, args){
  36. var me = this,
  37. id,
  38. call = function(){
  39. clearInterval(id);
  40. id = null;
  41. fn.apply(scope, args || []);
  42. };
  43. /**
  44. * Cancels any pending timeout and queues a new one
  45. * @param {Number} delay The milliseconds to delay
  46. * @param {Function} newFn (optional) Overrides function passed to constructor
  47. * @param {Object} newScope (optional) Overrides scope passed to constructor
  48. * @param {Array} newArgs (optional) Overrides args passed to constructor
  49. */
  50. me.delay = function(delay, newFn, newScope, newArgs){
  51. me.cancel();
  52. fn = newFn || fn;
  53. scope = newScope || scope;
  54. args = newArgs || args;
  55. id = setInterval(call, delay);
  56. };
  57. /**
  58. * Cancel the last queued timeout
  59. */
  60. me.cancel = function(){
  61. if(id){
  62. clearInterval(id);
  63. id = null;
  64. }
  65. };
  66. };