jquery.payWithTweet.js

(function($) {
    var win = null;
    $.fn.tweetAction = function(options, callback) {
        // Default parameters of the tweet popup:
        options = $.extend({
            url: window.location.href,
            cookies: true
        }, options);

        //the user has already tweeted -- callback immidiately and return
        if (readCookie("tweetToDownload") == "true" && options.cookies) {
            callback();
            return;
        }

        return this.click(function(e) {
            if (win) {
                // If a popup window is already shown,
                // do nothing;
                e.preventDefault();
                return;
            }

            var width = 550,
                height = 350,
                top = (window.screen.height - height) / 2,
                left = (window.screen.width - width) / 2;

            var config = [
                'scrollbars=yes', 'resizable=yes', 'toolbar=no', 'location=yes',
                'width=' + width, 'height=' + height, 'left=' + left, 'top=' + top
            ].join(',');

            // Opening a popup window pointing to the twitter intent API:
            win = window.open('http://twitter.com/intent/tweet?' + $.param(options), 'TweetWindow', config);

            // Checking whether the window is closed every 100 milliseconds.
            (function checkWindow() {
                try {
                    // Opera raises a security exception, so we
                    // need to put this code in a try/catch:
                    if (!win || win.closed) {
                        throw "Closed!";
                    } else {
                        setTimeout(checkWindow, 100);
                    }
                } catch (e) {
                    // Executing the callback, passed
                    // as an argument to the plugin.
                    win = null;
                    createCookie("tweetToDownload", true, 30);
                    callback();
                }
            })();
            e.preventDefault();
        });
    };

    function createCookie(name, value, days) {
        var expires;

        if (days) {
            var date = new Date();
            date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
            expires = "; expires=" + date.toGMTString();
        } else {
            expires = "";
        }
        document.cookie = encodeURIComponent(name) + "=" + encodeURIComponent(value) + expires + "; path=/";
    }

    function readCookie(name) {
        var nameEQ = encodeURIComponent(name) + "=";
        var ca = document.cookie.split(';');
        for (var i = 0; i < ca.length; i++) {
            var c = ca[i];
            while (c.charAt(0) === ' ') c = c.substring(1, c.length);
            if (c.indexOf(nameEQ) === 0) return decodeURIComponent(c.substring(nameEQ.length, c.length));
        }
        return null;
    }
})(jQuery);