Question

I had an idea to keep my users’ sessions alive by sending a webservice call, setting a timeout for a set amount of time (like 15 mins or so) then recall that same method.

Problem is the webservice appears to fire off continuously. Not every 15 mins like I thought.

A link can be found here: Fiddle

Code here:

(function($, window, document, undefined) {
    "use strict";

    var methods, 
        settings,
        timeout,
        type = 'sessionPing';

    methods = {
        init: function () { 
            settings = { time: 5000};

            methods.request.call(this);
        },

        request: function () { 
            console.log('just before clear' + timeout);
          clearTimeout(timeout);

            $.ajax({ type: 'POST',
                   url: '/echo/html/',
                   data: {
                    'html': 'Echo!'
                   },
                   success: function(data) {
                     timeout = setTimeout(methods.request(), settings.time);  
                       console.log('in success ' + timeout);
                   },
                   dataType: 'html'
                });  
        }
    };

    $.sessionPing = function(method) {
        // Method calling logic
        if (methods[method]) {
            return methods[method].apply(this, Array.prototype.slice.call(arguments, 1));
        } else if (typeof method === 'object' || !method) {
            return methods.init.apply(this, arguments);
        } else {
            $.error('Method ' + method + ' does not exist on jQuery.timeSince');
        }
    };

}(jQuery, window, document));


$(function() {
    $.sessionPing();
});    

Answer 1

timeout = setTimeout(methods.request(), settings.time);

Your parentheses there will automatically run methods.request, which in turn will run code that automatically runs methods.request on down the line; basically, the method will execute over and over again, binding increasingly more versions of itself to your interval.

timeout = setTimeout(methods.request, settings.time);

That’s what you’re looking for: just passing the function signature instead of passing a function that executes as a side-effect.