js能否判断一个链接的http状态

Question

可以向地址发送请求 js+ajax，然后看返回状态是否为404,当然你得有权限，能模拟提交参数

Answer 1

IE启用跨域请求，用ajax的status属性可以得到对应的状态

Answer 2

var url = "http://bbs.csdn.net/topics/3907043101";
jQuery.ajax({
            type: "post",
            async: false,
            dataType: "json",
            url: "Default.aspx/UrlIsExist",
            contentType: "application/json; charset=utf-8",
            cache: false,
            data: '{url:\"' + url + '"}',
            success: function (data) {
                if (data.d == "true") {
                   //地址可用
                }else{
                   //地址不存在 
                }
            },
            Error: function (error) {
                alert(error);
            }
        });
[WebMethod]
private static string UrlExistsUsingHttpWebRequest(string url)
    {
        HttpWebRequest webReqst = (HttpWebRequest)WebRequest.Create(url);
        webReqst.Method = "GET";
        webReqst.KeepAlive = true;
        webReqst.Timeout = 300;
        string result = false;
        try
        {
            HttpWebResponse webResponse = (HttpWebResponse)webReqst.GetResponse();            if (webResponse.StatusCode == HttpStatusCode.OK && webResponse.ContentLength < 1024 * 1024)
            {
                result = "true";
            }
        }
        catch
        {
            result = "false";
        }
        return result;    }