我创建了一个长轮询 JSON 源并使用结果更新 div 的脚本。我的代码发布在下面。
代码工作正常，我请求的数据被正确抓取和输出。该代码检查 JSON 并抓取 2 张图像和一些文本数据。
问题是它不断刷新数据并不断下载图像，导致服务器负载和带宽消耗很高（显然现在这很小，但随着我的项目完成会增加）。这也导致我无法选择 div 中的文本，并且图像在重新加载时闪烁，这两者都是我当前代码的不良后果。
我希望能够获取数据并显示它，并且在 JSON 响应中的数据实际发生变化之前根本不更新它，我假设我需要用时间戳做一些事情？我尝试使用 JSON 中的 first_aired 键创建 lastupdate 时间戳，但它不起作用，我不确定我是否犯了错误，或者我是否在吠叫错误的树。
有人可以看看我拥有的代码，或许可以指出我需要做什么的正确方向吗？
var lastupdate = 0;
// call getData when the document has loaded
$(document).ready(function(){
getData(lastupdate);
});
var getData = function(lastupdate) {
$.ajax({
type: "GET",
url: 'http://api.trakt.tv/user/watching.json/apikey/user/lastupdate='+lastupdate+'&callback=?',
dataType: 'jsonp',
async: true,
cache: false,
// timeout after 5 minutes, shut process down and restart
timeout:300000,
// process a successful response
success: function(watching_now) {
if (!jQuery.isEmptyObject(watching_now)) {
//console.log(watching_now);
var airDate = watching_now.episode.first_aired;
var showTitle = watching_now.show.title;
var showPoster = watching_now.show.images.poster;
var showURL = watching_now.show.url;
var episodeTitle = watching_now.episode.title;
var episodeScreen = watching_now.episode.images.screen;
var episodeNumber = watching_now.episode.number;
var episodeSeason = watching_now.episode.season;
$('#watching-now').html('<div class="screencap"><img src="' + episodeScreen +' " width="240" height="150" /></div><div class="poster"><a href="'+showURL+'" target="_blank"><img src="' + showPoster +'" width="85" height="120" /></a></div><div class="watching-info">'+episodeSeason+'x'+episodeNumber+' - '+episodeTitle+'</div>')
}
else {
$('#watching-now').html('You are not currently watching anything')
}
// set lastupdate
lastupdate = watching_now.airDate;
// call again in 1 second
setTimeout('getData('+lastupdate+');', 1000);
},
// handle error
error: function(XMLHttpRequest, textStatus, errorThrown){
// try again in 10 seconds if there was a request error
setTimeout('getData('+lastupdate+');', 10000);
},
});
};
这是我正在获取信息表单的 JSON：
{"type":"episode","action":"watching","show":{"title":"Stargate Atlantis","year":2004,"url":"http://trakt.tv/show/stargate-atlantis","imdb_id":"tt0374455","tvdb_id":"70851","tvrage_id":"5324","first_aired":1089961200,"country":"United States","overview":"The story of Stargate Atlantis follows the cliffhanger episode on Stargate SG-1's seventh season finale \"Lost City\", where SG-1 found an outpost made by the race known as the Ancients in Antarctica. After the events of Stargate SG-1 season eight premiere \"New Order\", the Stargate Command sends an international team to investigate the outpost. Soon, Dr. Daniel Jackson discovers the location of the greatest city created by the Ancients, Atlantis. The story unfolds when the members of the expedition encounter the Wraith, the race that defeated the Ancients ten thousand years ago.","runtime":60,"network":"Syfy","air_day":"Monday","air_time":"9:00pm","certification":"TV-PG","images":{"poster":"http://trakt.us/images/posters/329.3.jpg","fanart":"http://trakt.us/images/fanart/329.3.jpg","banner":"http://trakt.us/images/banners/329.3.jpg"},"genres":["Action","Adventure","Science Fiction"]},"episode":{"season":3,"number":10,"title":"The Return (1)","overview":"The Atlantis expedition is stunned to learn that a ship full of Ancients is returning to reclaim their lost city. ","first_aired":1158908400,"url":"http://trakt.tv/show/stargate-atlantis/season/3/episode/10","images":{"screen":"http://trakt.us/images/episodes/329-3-10.3.jpg"}}}
如果您需要更多信息，请询问，我会尽我所能提供。
干杯