可以使用Javascript来检测重定向的图像SRC（在任何流行的浏览器中）？ [英] Can Javascript be used to detect a redirected image SRC (in any popular browser)?

问题描述

1. 浏览器加载< img src = http://example.net/lolcat.png>


2. example.net redirects lolcat.png 至 http://static.example.net/bandwidth-exceeded.gif

我可以检测到吗？

跨浏览器并不重要，只需查找可在任何1个热门浏览器中使用的选项。

到目前为止，我最好的选择是了解占位符图像的大小，通过查看图像大小onload（在支持图像标签中的onload事件的浏览器中）获得或许，并通过快速XHR请求通知后端我们有一个可能。

解决方案

我检查了以下代码：

  var a = new Image（）; a.src =的 http：//example.com/image.png; 
 alert（a.width）; 
  

在这种情况下，返回0，因为图像不存在。

在链接文本我发现很多可能值得检查的属性。如果失败，您可能需要查看jQuery和AJAX。

修改：

_{在firefox firebug上测试}

  var a = new Image（）; 
 a.src ='http：//l.yimg.com/g/images/photo_unavailable_m.gif'; 
 console.log（a.width）; //图像存在并返回240 
 
 var b = new Image（）; 
 b.src ='http：//farm3.static.flickr.com/2560/4098180849_729ef4f6ef_m.jpg'; 
 console.log（b.width）; //图像不存在（重新直接）并返回0 
  

I'm guessing nope, but you never know.

1. Browser loads <img src="http://example.net/lolcat.png">
2. example.net redirects lolcat.png to http://static.example.net/bandwidth-exceeded.gif

Can I detect this?

Cross-browser isn't important, just looking for an option that will work in any 1 popular browser.

So far my best option is knowing the size of the placeholder image, getting a "maybe" by looking at the image size onload (in browsers that support onload events in image tags), and making a quick XHR request notifying the backend that we've got a maybe.

解决方案

I checked with the following code:

var a=new Image(); a.src='http://example.com/image.png';
alert( a.width );

which in this case returns 0 since the image doesn't exist.

On link text I found quite a few properties that might be worth checking out. And if that fails you might want to look into jQuery and AJAX.

Edit:
_{tested on firefox firebug}

var a=new Image(); 
a.src='http://l.yimg.com/g/images/photo_unavailable_m.gif';
console.log(a.width); // the image exists and returns 240

var b=new Image(); 
b.src='http://farm3.static.flickr.com/2560/4098180849_729ef4f6ef_m.jpg';
console.log(b.width); // the image does not exist (re-direct) and returns 0

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