Easy polling in jQuery

polling.example.js

$.poll({
  url: '/status.json'
, dataType: 'json'
, timeout: 1000       // initial timeout of 1s
, multiplier: 2       // double the timeout each time
, retries: 10         // maximum of ten tries
, until: function(data) { return data.status == 'done'; }
, success: function(data) { alert(data.message); }
});

polling.js

(function() {
  $.poll = function(options) {
    options = options || {};
    
    var timeout    = options.timeout    || 5000,
        maxTimeout = options.maxTimeout || 30000,
        multiplier = options.multiplier || 1,
        retries    = options.retries    || -1, // retry indefinitely
        callback   = options.until;
        
    
    var f = function() {
      $.ajax($.extend({}, options, {
        success: function() {
          if (callback && callback.apply(this, arguments)) {
            options.success && options.success.apply(this, arguments);
          } else if (retries) {
            setTimeout(f, timeout);
            timeout = Math.min(timeout * multiplier, maxTimeout);
            retries -= 1;
          }
        }
      }));
    }
    f();
  };
})();