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/* Polls the server for new JSON data at a defined interval. Requests are garunteed to not stack up on each other.
Example Usage:
var poller = $.poller({
url: function(head){
var base = '/messages/';
return (head) ? (base + '?since_id=' + head.result.id) : base;
},
receive: function(set){
$(set).each(function(json){
$('#messages').append('<div>' + json.message.id +' was received!</div>');
});
}
});
poller.start();
Ugliness
- The way head is handled seems inconsistent
- There has to be a better way to wrap a value into a function
- Not sure how "this" and "that" references are handled in jQuery
*/
(function($){
$.extend({
poller: function poller(options){
options = $.extend({
interval: 1000,
head: function(set){ return set[0]; }
}, options);
// Wraps the URL into a function so we can handle pagination in cases where we need
// to build an URL based off of what is given in head.
if (typeof options.url != 'function'){
var __url__ = options.url;
options.url = function wrappedUrl(head){ return __url__; };
}
var head;
// This is our interupt if we want to stop polling
var polling = true;
// HACK Is 'that' the correct style in jQuery???
var that = {
start: function start(){
$.getJSON(options.url(head), function(set){
head = options.head(set);
console.log('parseHead', head);
if (options.receive) { options.receive(set, that); }
if (polling) {
setTimeout(function(){
$.poller(options).start();
}, options.interval);
}
});
return that;
},
stop: function stop(){
polling = false;
return that;
},
options: options,
head: function(){ return head; }
};
return that;
}
});
})(jQuery);
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