252 lines
10 KiB
JavaScript
Vendored
252 lines
10 KiB
JavaScript
Vendored
/*!
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* jQuery throttle / debounce - v1.1 - 3/7/2010
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* http://benalman.com/projects/jquery-throttle-debounce-plugin/
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*
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* Copyright (c) 2010 "Cowboy" Ben Alman
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* Dual licensed under the MIT and GPL licenses.
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* http://benalman.com/about/license/
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*/
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// Script: jQuery throttle / debounce: Sometimes, less is more!
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//
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// *Version: 1.1, Last updated: 3/7/2010*
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//
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// Project Home - http://benalman.com/projects/jquery-throttle-debounce-plugin/
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// GitHub - http://github.com/cowboy/jquery-throttle-debounce/
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// Source - http://github.com/cowboy/jquery-throttle-debounce/raw/master/jquery.ba-throttle-debounce.js
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// (Minified) - http://github.com/cowboy/jquery-throttle-debounce/raw/master/jquery.ba-throttle-debounce.min.js (0.7kb)
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//
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// About: License
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//
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// Copyright (c) 2010 "Cowboy" Ben Alman,
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// Dual licensed under the MIT and GPL licenses.
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// http://benalman.com/about/license/
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//
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// About: Examples
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//
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// These working examples, complete with fully commented code, illustrate a few
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// ways in which this plugin can be used.
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//
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// Throttle - http://benalman.com/code/projects/jquery-throttle-debounce/examples/throttle/
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// Debounce - http://benalman.com/code/projects/jquery-throttle-debounce/examples/debounce/
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//
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// About: Support and Testing
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//
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// Information about what version or versions of jQuery this plugin has been
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// tested with, what browsers it has been tested in, and where the unit tests
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// reside (so you can test it yourself).
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//
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// jQuery Versions - none, 1.3.2, 1.4.2
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// Browsers Tested - Internet Explorer 6-8, Firefox 2-3.6, Safari 3-4, Chrome 4-5, Opera 9.6-10.1.
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// Unit Tests - http://benalman.com/code/projects/jquery-throttle-debounce/unit/
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//
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// About: Release History
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//
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// 1.1 - (3/7/2010) Fixed a bug in <jQuery.throttle> where trailing callbacks
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// executed later than they should. Reworked a fair amount of internal
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// logic as well.
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// 1.0 - (3/6/2010) Initial release as a stand-alone project. Migrated over
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// from jquery-misc repo v0.4 to jquery-throttle repo v1.0, added the
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// no_trailing throttle parameter and debounce functionality.
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//
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// Topic: Note for non-jQuery users
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//
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// jQuery isn't actually required for this plugin, because nothing internal
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// uses any jQuery methods or properties. jQuery is just used as a namespace
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// under which these methods can exist.
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//
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// Since jQuery isn't actually required for this plugin, if jQuery doesn't exist
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// when this plugin is loaded, the method described below will be created in
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// the `Cowboy` namespace. Usage will be exactly the same, but instead of
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// $.method() or jQuery.method(), you'll need to use Cowboy.method().
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(function(window,undefined){
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'$:nomunge'; // Used by YUI compressor.
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// Since jQuery really isn't required for this plugin, use `jQuery` as the
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// namespace only if it already exists, otherwise use the `Cowboy` namespace,
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// creating it if necessary.
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var $ = window.jQuery || window.Cowboy || ( window.Cowboy = {} ),
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// Internal method reference.
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jq_throttle;
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// Method: jQuery.throttle
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//
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// Throttle execution of a function. Especially useful for rate limiting
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// execution of handlers on events like resize and scroll. If you want to
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// rate-limit execution of a function to a single time, see the
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// <jQuery.debounce> method.
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//
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// In this visualization, | is a throttled-function call and X is the actual
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// callback execution:
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//
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// > Throttled with `no_trailing` specified as false or unspecified:
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// > ||||||||||||||||||||||||| (pause) |||||||||||||||||||||||||
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// > X X X X X X X X X X X X
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// >
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// > Throttled with `no_trailing` specified as true:
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// > ||||||||||||||||||||||||| (pause) |||||||||||||||||||||||||
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// > X X X X X X X X X X
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//
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// Usage:
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//
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// > var throttled = jQuery.throttle( delay, [ no_trailing, ] callback );
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// >
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// > jQuery('selector').bind( 'someevent', throttled );
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// > jQuery('selector').unbind( 'someevent', throttled );
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//
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// This also works in jQuery 1.4+:
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//
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// > jQuery('selector').bind( 'someevent', jQuery.throttle( delay, [ no_trailing, ] callback ) );
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// > jQuery('selector').unbind( 'someevent', callback );
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//
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// Arguments:
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//
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// delay - (Number) A zero-or-greater delay in milliseconds. For event
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// callbacks, values around 100 or 250 (or even higher) are most useful.
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// no_trailing - (Boolean) Optional, defaults to false. If no_trailing is
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// true, callback will only execute every `delay` milliseconds while the
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// throttled-function is being called. If no_trailing is false or
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// unspecified, callback will be executed one final time after the last
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// throttled-function call. (After the throttled-function has not been
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// called for `delay` milliseconds, the internal counter is reset)
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// callback - (Function) A function to be executed after delay milliseconds.
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// The `this` context and all arguments are passed through, as-is, to
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// `callback` when the throttled-function is executed.
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//
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// Returns:
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//
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// (Function) A new, throttled, function.
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$.throttle = jq_throttle = function( delay, no_trailing, callback, debounce_mode ) {
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// After wrapper has stopped being called, this timeout ensures that
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// `callback` is executed at the proper times in `throttle` and `end`
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// debounce modes.
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var timeout_id,
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// Keep track of the last time `callback` was executed.
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last_exec = 0;
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// `no_trailing` defaults to falsy.
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if ( typeof no_trailing !== 'boolean' ) {
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debounce_mode = callback;
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callback = no_trailing;
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no_trailing = undefined;
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}
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// The `wrapper` function encapsulates all of the throttling / debouncing
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// functionality and when executed will limit the rate at which `callback`
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// is executed.
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function wrapper() {
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var that = this,
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elapsed = +new Date() - last_exec,
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args = arguments;
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// Execute `callback` and update the `last_exec` timestamp.
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function exec() {
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last_exec = +new Date();
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callback.apply( that, args );
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};
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// If `debounce_mode` is true (at_begin) this is used to clear the flag
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// to allow future `callback` executions.
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function clear() {
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timeout_id = undefined;
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};
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if ( debounce_mode && !timeout_id ) {
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// Since `wrapper` is being called for the first time and
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// `debounce_mode` is true (at_begin), execute `callback`.
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exec();
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}
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// Clear any existing timeout.
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timeout_id && clearTimeout( timeout_id );
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if ( debounce_mode === undefined && elapsed > delay ) {
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// In throttle mode, if `delay` time has been exceeded, execute
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// `callback`.
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exec();
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} else if ( no_trailing !== true ) {
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// In trailing throttle mode, since `delay` time has not been
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// exceeded, schedule `callback` to execute `delay` ms after most
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// recent execution.
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//
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// If `debounce_mode` is true (at_begin), schedule `clear` to execute
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// after `delay` ms.
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//
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// If `debounce_mode` is false (at end), schedule `callback` to
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// execute after `delay` ms.
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timeout_id = setTimeout( debounce_mode ? clear : exec, debounce_mode === undefined ? delay - elapsed : delay );
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}
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};
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// Set the guid of `wrapper` function to the same of original callback, so
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// it can be removed in jQuery 1.4+ .unbind or .die by using the original
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// callback as a reference.
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if ( $.guid ) {
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wrapper.guid = callback.guid = callback.guid || $.guid++;
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}
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// Return the wrapper function.
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return wrapper;
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};
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// Method: jQuery.debounce
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//
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// Debounce execution of a function. Debouncing, unlike throttling,
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// guarantees that a function is only executed a single time, either at the
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// very beginning of a series of calls, or at the very end. If you want to
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// simply rate-limit execution of a function, see the <jQuery.throttle>
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// method.
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//
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// In this visualization, | is a debounced-function call and X is the actual
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// callback execution:
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//
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// > Debounced with `at_begin` specified as false or unspecified:
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// > ||||||||||||||||||||||||| (pause) |||||||||||||||||||||||||
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// > X X
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// >
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// > Debounced with `at_begin` specified as true:
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// > ||||||||||||||||||||||||| (pause) |||||||||||||||||||||||||
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// > X X
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//
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// Usage:
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//
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// > var debounced = jQuery.debounce( delay, [ at_begin, ] callback );
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// >
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// > jQuery('selector').bind( 'someevent', debounced );
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// > jQuery('selector').unbind( 'someevent', debounced );
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//
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// This also works in jQuery 1.4+:
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//
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// > jQuery('selector').bind( 'someevent', jQuery.debounce( delay, [ at_begin, ] callback ) );
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// > jQuery('selector').unbind( 'someevent', callback );
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//
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// Arguments:
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//
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// delay - (Number) A zero-or-greater delay in milliseconds. For event
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// callbacks, values around 100 or 250 (or even higher) are most useful.
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// at_begin - (Boolean) Optional, defaults to false. If at_begin is false or
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// unspecified, callback will only be executed `delay` milliseconds after
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// the last debounced-function call. If at_begin is true, callback will be
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// executed only at the first debounced-function call. (After the
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// throttled-function has not been called for `delay` milliseconds, the
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// internal counter is reset)
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// callback - (Function) A function to be executed after delay milliseconds.
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// The `this` context and all arguments are passed through, as-is, to
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// `callback` when the debounced-function is executed.
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//
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// Returns:
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//
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// (Function) A new, debounced, function.
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$.debounce = function( delay, at_begin, callback ) {
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return callback === undefined
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? jq_throttle( delay, at_begin, false )
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: jq_throttle( delay, callback, at_begin !== false );
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};
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})(this);
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