jquery.periodic.js
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/*!
* jQuery periodic plugin
*
* Copyright 2010, Tom Anderson
* Dual licensed under the MIT or GPL Version 2 licenses.
*
*/
$.periodic = function (options, callback) {
// if the first argument is a function then assume the options aren't being passed
if (jQuery.isFunction(options)) {
callback = options;
options = {};
}
// Merge passed settings with default values
var settings = jQuery.extend({}, jQuery.periodic.defaults, {
ajax_complete : ajaxComplete,
increment : increment,
reset : reset,
cancel : cancel
}, options);
// bookkeeping variables
settings.cur_period = settings.period;
settings.tid = false;
var prev_ajax_response = '';
run();
// return settings so user can tweak them externally
return settings;
// run (or restart if already running) the looping construct
function run() {
// clear/stop existing timer (multiple calls to run() won't result in multiple timers)
cancel();
// let it rip!
settings.tid = setTimeout(function() {
// set the context (this) for the callback to the settings object
callback.call(settings);
// compute the next value for cur_period
increment();
// queue up the next run
if(settings.tid)
run();
}, settings.cur_period);
}
// utility function for use with ajax calls
function ajaxComplete(xhr, status) {
if (status === 'success' && prev_ajax_response !== xhr.responseText) {
// reset the period whenever the response changes
prev_ajax_response = xhr.responseText;
reset();
}
}
// compute the next delay
function increment() {
settings.cur_period *= settings.decay;
if (settings.cur_period < settings.period) {
// don't let it drop below the minimum
reset();
} else if (settings.cur_period > settings.max_period) {
settings.cur_period = settings.max_period;
if (settings.on_max !== undefined) {
// call the user-supplied callback if we reach max_period
settings.on_max.call(settings);
}
}
}
function reset() {
settings.cur_period = settings.period;
// restart with the new timeout
run();
}
function cancel() {
clearTimeout(settings.tid);
settings.tid = null;
}
// other functions we might want to implement
function pause() {}
function resume() {}
function log() {}
};
jQuery.periodic.defaults = {
period : 4000, // 4 sec.
max_period : 1800000, // 30 min.
decay : 1.5, // time period multiplier
on_max : undefined // called if max_period is reached
};