A port of Prototype's Ajax.PeriodicalUpdater function to jQuery.

Basically, this function polls some remote service at fairly regular internvals, and (optionally) processes the result via a callback. The period of calls will decay as long as the same response keeps coming back from the server (either in the form of repeated data or in the form of a 304 Not Modified status), which reduces the load on the server naturally. The first Ajax call happens as a page 'onReady' handler (ie: the jQuery(function) call), so it is safe to put the PeriodicalUpdater call anywhere on the page.

Usage:

    $.PeriodicalUpdater('/path/to/service', {
        url: url,         // URL of ajax request
        cache: false,     // By default, don't allow caching
        method: 'GET',    // method; get or post
        data: '',         // array of values to be passed to the page - e.g. {name: "John", greeting: "hello"}
        minTimeout: 1000, // starting value for the timeout in milliseconds
        maxTimeout:64000, // maximum length of time between requests
        multiplier: 2,    // if set to 2, timerInterval will double each time the response hasn't changed (up to maxTimeout)
        maxCalls: 0,      // maximum number of calls. 0 = no limit.
        maxCallsCallback: null, // The callback to execute when we reach our max number of calls
        autoStop: 0,      // automatically stop requests after this many returns of the same data. 0 = disabled
        autoStopCallback: null, // The callback to execute when we autoStop
        cookie: false,    // whether (and how) to store a cookie
        runatonce: false, // Whether to fire initially or wait
        verbose: 0        // The level to be logging at: 0 = none; 1 = some; 2 = all
    }, function(remoteData, success, xhr, handle) {
        // Process the new data (only called when there was a change)
                // For a description of "success", see $.ajax documentation
    });

        // You can also do a bound version: identical to above except that the callback function
        // has 'this' assigned to the JQuery object that you call it on.
        $('.myClass').PeriodicalUpdater('/path/to/service', { /* ... */ }, function(/*...*/) {
            // this is $('.myClass')
        });

Data:

The data value can be one of three things:

• A scalar, in which case it will be used constantly.
• A JavaScript map/object, in which case it will be turned into key/value pairs by jQuery
• An anonymous function, in which case it will be executed before each AJAX call. See jQuery.ajax for more information.

Cookie:

The cookie value will store the timeout of the previous PeriodicalUpdater between page loads. It uses the JQuery-Cookie plugin (imported automatically by the script) to store these values. The value for the cookie configuration value can be one of three things:

• A scalar, in which case it is treated as the cookie name
• A JavaScript map/object, in which case you can specify the cookie name as the name property, and you can additionally specify any configuration value for the JQuery-Cookie plugin in order to configure the cookie.
• A boolean, which signals to use a cookie if true, and not to use a cookie if false.

If you don't specify a cookie name, the cookie name defaults to the PeriodicalUpdater's url. WARNING: If you use two PeriodicalUpdaters with the same cookie name, they will each overwrite the other's value, resulting in wonky timeout behavior.

Other Configuration Data:

Any of the other standard $.ajax configuration options can be passed to the setting map, including the AJAX callbacks. The only exception is the flag that treats modifications as errors. That is always going to be true.

Function Return Value (Handle):

The function call returns a handle. You can call .stop() on this handle in order to stop the updating and ignore any subsequent responses. If the maximum number of calls, .stop(), or the autoStop has been triggered, you can restart the updater using .restart() on the handle. You can also call .send() on the handle to force a send of the AJAX request. This handle is also passed into the callback functions as the fourth argument.

More Information:

For more info about the motivation for this plugin, including its advantages over the deprecated 360innovate version, see the blog post on EnfranchisedMind.

See the source file for license terms.