读取图像的绝对重定向SRC属性URL [英] Read the absolute redirected SRC attribute URL for an image
问题描述
我正在使用Twitter头像API在客户端获取用户的头像URL，我想缓存响应，但不是常规JSON（或者实际上是任何其他类型），他们只是发出302重定向。
I'm using the Twitter avatar API to fetch a user's avatar URL on the client-side, and I'd like to cache the response, but instead of a regular JSON (or indeed, any other type), they just issue a 302 redirect.
这不起作用（因为它是跨域）：
This doesn't work (because it's cross domain):
jQuery.getJSON('https://api.twitter.com/1/users/profile_image/60173.json',
function(data, status, jqxhr){
console.log("data: ", data);
console.log("status: ", status);
console.log("jqxhr: ", jqxhr);
console.log(jqxhr.getResponseHeader('Location'));
console.log(jqxhr.getAllResponseHeaders());
})
数据为空，状态为'success'，jqhxr返回jqxhr对象，但getResponseHeader（）和getResponseHeaders（）为null，因为它是跨域调用而不是真正的XMLHTTP打电话。
Data is empty, status is 'success', jqhxr returns a jqxhr object, but the getResponseHeader() and getResponseHeaders() are null because it's a cross-domain call rather than a true XMLHTTP call.
所以我想我可以使用load（）事件来显示我的实际网址法师在302发生之后。我试过这个：
So I thought I might be able to use the load() event to show the actual url of the image after the 302 had happened. I tried this:
function avatar_loaded(img) {
console.log("We loaded an avatar for %s (img)[0].src is %o
attr('src') is %o getAttribute('src') is %o", img, jQuery(img)[0].src, jQuery(img).attr('src'), img.getAttribute("src"));
}
var avatar_url = "https://api.twitter.com/1/users/profile_image/60173";
jQuery('body').append("<img onload='avatar_loaded(this)' src='" +
avatar_url + "' width='0' height='0'>");
你会看到avatar_loaded函数被调用两次。一旦使用了初始的img src（https://api.twitter.com/1/users/profile_image/60173），然后再次使用302ed实际图像url http://a1.twimg.com/profile_images/1272489576/Photo_38_normal.jpg
You'll see that the avatar_loaded function gets called twice. Once with the initial img src (https://api.twitter.com/1/users/profile_image/60173) and then again, presumably with the 302ed actual image url http://a1.twimg.com/profile_images/1272489576/Photo_38_normal.jpg
但无论我尝试什么，我都无法读取重定向的绝对URL。还有其他任何想法吗？
But I can't read the redirected absolute URL no matter what I try. Any other ideas?
编辑：我不想把它变成时间接收器，所以我只是用了
I Didn't want this to turn into a time-sink, so I just used the
http://api.twitter.com/1/users/show.json?user_id=
API调用。我想象这需要对受保护用户进行经过身份验证的调用，但它并不是那么好用。
API call. I'd imagined that this would require an authenticated call for protected users, it doesn't so it's fine to use.
推荐答案
而不是使用
http://api.twitter.com/1/users/profile_image/<user_id>
API调用，我用过
http://api.twitter.com/1/users/show.json?user_id=
而是从那里提取头像URL。它不是轻量级的，因为它也会返回大量其他用户数据，但即使是受保护的用户头像也无需验证即可返回，因此它是一个合适的替代品。
instead and extracted the avatar URL from there. It's not as light-weight because it returns a raft of other user data too, but even protected users avatars are returned without the need for authentication, so it's a suitable replacement.
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