Javascript/Ajax中的HTTP HEAD请求?

Is it possible to do a HTTP Head request solely using an XMLHTTPRequest in JavaScript?

是否可以仅使用JavaScript中的XMLHTTPRequest来执行HTTP Head请求?

My motivation is to conserve bandwidth.

我的动机是节省带宽。

If not, is it possible to fake it?

如果不是，有可能伪造吗?

2 个解决方案

#1

Easy, just use the HEAD method, instead of GET or POST:

简单，只需使用HEAD方法，而不是GET或POST:

function UrlExists(url, callback)
{
    var http = new XMLHttpRequest();
    http.open('HEAD', url);
    http.onreadystatechange = function() {
        if (this.readyState == this.DONE) {
            callback(this.status != 404);
        }
    };
    http.send();
}

This is just a short example to show how to use the HEAD method. Production code may need more fine-grained callbacks for different result states (success, failure, timeout), and may use different event handlers (onload, onerror and ontimeout rather than onreadystatechange).

这只是一个简短的示例，演示如何使用HEAD方法。生产代码可能需要对不同的结果状态(成功、失败、超时)进行更细粒度的回调，并且可能使用不同的事件处理程序(onload、onerror和ontimeout，而不是onreadystatechange)。

#2

An XMLHTTPRequest object should have

XMLHTTPRequest对象应该有

getAllResponseHeaders();
getResponseHeader("header-name")

defined on it

上定义它

#1