Javascript 检测 iframe 内容是否加载成功
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Detect if the iframe content has loaded successfully
提问by Javier Orellana
I have a widget that contains an iframe. The user can configure the url of this iframe, but if the url could not be loaded (it does not exists or the user does not have access to internet) then the iframe should failover to a default offline page.
我有一个包含 iframe 的小部件。用户可以配置此 iframe 的 url，但如果 url 无法加载（它不存在或用户无法访问互联网），则 iframe 应故障转移到默认的离线页面。
The question is, how can I detect if the iframe could be loaded or not? I tried subscribing to the 'load' event, and, if this event is not fired after some time then I failover, but this only works in Firefox, since IE and Chrome fires the 'load' event when the "Page Not Found" is displayed.
问题是，如何检测 iframe 是否可以加载？我尝试订阅 'load' 事件，并且，如果此事件在一段时间后未触发，则我进行故障转移，但这仅适用于 Firefox，因为 IE 和 Chrome 在“找不到页面”时触发 'load' 事件显示。
采纳答案by Adilson de Almeida Jr
Nowadays the browsers have a series of security limitations that keep you away from the content of an iframe (if it isn′t of your domain).
现在浏览器有一系列安全限制，使您远离 iframe 的内容（如果它不是您的域）。
If you really need that functionality, you have to build a server page that have to work as a proxy, that receive the url as a parameter, test if it is a valid url, and does the redirect or display the error page.
如果您确实需要该功能，则必须构建一个必须作为代理工作的服务器页面，该页面接收 url 作为参数，测试它是否为有效 url，并执行重定向或显示错误页面。
回答by RobinBrouwer
I found the following link via Google: http://wordpressapi.com/2010/01/28/check-iframes-loaded-completely-browser/
我通过谷歌找到了以下链接：http: //wordpressapi.com/2010/01/28/check-iframes-loaded-completely-browser/
Don't know if it solves the 'Page Not Found' issue.
不知道它是否解决了“找不到页面”的问题。
<script type="javascript">
var iframe = document.createElement("iframe");
iframe.src = "http://www.your_iframe.com/";
if (navigator.userAgent.indexOf("MSIE") > -1 && !window.opera) {
iframe.onreadystatechange = function(){
if (iframe.readyState == "complete"){
alert("Iframe is now loaded.");
}
};
} else {
iframe.onload = function(){
alert("Iframe is now loaded.");
};
}
</script>
I haven't tried it myself, so I don't know if it works. Good luck!
我自己没有尝试过，所以我不知道它是否有效。祝你好运！
回答by Henry
If you control the content of the iframe, the iframe can send a message to the parent.
如果您控制 iframe 的内容，则 iframe 可以向父级发送消息。
parent.postMessage('iframeIsDone', '*');
The parent callback listens for the message.
父回调侦听消息。
var attachFuncEvent = "message";
var attachFunc = window.addEventListener ;
if (! window.addEventListener) {
attachFunc = window.attachEvent;
attachFuncEvent = "onmessage";
}
attachFunc(attachFuncEvent, function(event) {
if (event.data == 'iframeIsDone') { // iframe is done callback here
}
});
回答by Jens Timmerman
How about checking if the url is available and only then setting the actual url of the iframe? e.g. with JQuery
如何检查 url 是否可用，然后才设置 iframe 的实际 url？例如使用 JQuery
var url = "google.com"
var loading_url = "/empty.html"
document.getElementById("iframe").src = loading_url;
$.ajax({
url: url,
type: 'GET',
complete: function(e, xhr, settings){
if(e.status === 200){
document.getElementById("iframe").src = url;
}
}
});
Edit: This does not seem to work cross domain, the status code is 0 in those cases.
编辑：这似乎不适用于跨域，在这些情况下状态代码为 0。
回答by DVK
If you have control over the contents of the iframe (e.g. you can add arbitrary code to the page), you can try to implement a special function in each of them, then in your page, you call that function and catch an error (via window.onerrorhandler) if the function called via eval fails because the page didn't load.
如果您可以控制 iframe 的内容（例如，您可以向页面添加任意代码），您可以尝试在每个 iframe 中实现一个特殊函数，然后在您的页面中，调用该函数并捕获错误（通过window.onerrorhandler) 如果通过 eval 调用的函数由于页面未加载而失败。
Here's example code: http://www.tek-tips.com/viewthread.cfm?qid=1114265&page=420
这是示例代码：http: //www.tek-tips.com/viewthread.cfm?qid=1114265&page=420
回答by Bitsplitter
After the onload fires, you can scavenge the content of the iframe to see if it contains a usefull page or not. You'd have to make this browser specifuc unfortunately because they all display a different "page not found" message.
在 onload 触发后，您可以清除 iframe 的内容以查看它是否包含有用的页面。不幸的是，您必须使此浏览器具体化，因为它们都显示不同的“找不到页面”消息。
For more info, take a look here at http://roneiv.wordpress.com/2008/01/18/get-the-content-of-an-iframe-in-javascript-crossbrowser-solution-for-both-ie-and-firefox/
