用js取得服务器响应的头部信息_js获取响应头的参数-优快云博客

本文介绍如何使用JavaScript中的XMLHttpRequest对象获取服务器响应的头部信息，包括设置请求、监听状态变化以及解析响应头数据。

var xmlHttp;

var requestType = "";

function createXMLHttpRequest() {

    if (window.ActiveXObject) {

        xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");

    }

    else if (window.XMLHttpRequest) {

        xmlHttp = new XMLHttpRequest();

    }

}

function doHeadRequest(request, url) {

    requestType = request;

    createXMLHttpRequest();

    xmlHttp.onreadystatechange = handleStateChange;

    xmlHttp.open("HEAD", url, true);

    xmlHttp.send(null);

}

function handleStateChange() {

    if(xmlHttp.readyState == 4) {

        if(requestType == "allResponseHeaders") {

            getAllResponseHeaders();

        }

        else if(requestType == "lastModified") {

            getLastModified();

        }

        else if(requestType == "isResourceAvailable") {

            getIsResourceAvailable();

        }

    }

}

function getAllResponseHeaders() {

    alert(xmlHttp.getAllResponseHeaders());

}

function getLastModified() {

    alert("Last Modified: " + xmlHttp.getResponseHeader("Last-Modified"));

}

function getIsResourceAvailable() {

    if(xmlHttp.status == 200) {

        alert("Successful response");

    }

    else if(xmlHttp.status == 404) {

        alert("Resource is unavailable");

    }

    else {

        alert("Unexpected response status: " + xmlHttp.status);

    }

}