responseXML的是空
问题描述：
url = "http://localhost/xml.php?type=xml";
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
xmlhttp.open("GET", url, true);
xmlhttp.setRequestHeader('Content-Type', 'text/xml');
xmlhttp.send(null);
}
else if (window.ActiveXObject) {
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
if (xmlhttp) {
xmlhttp.open("GET", url, true);
xmlhttp.setRequestHeader('Content-Type', 'text/xml');
xmlhttp.send();
}
}
alert(xmlhttp.responseXML); //returns null
XML文件
XML file
<?xml version="1.0" encoding="UTF-8" ?>
<main>
<food>
<type>6</type>
<region>5676</region>
</food>
<food>
<type>6</type>
<region>5676</region>
</food>
</main>
任何人有想法，为什么 xmlhttp.responseXML 正在恢复为空？
答
您的HTTP请求是异步的。 xmlhttp.responseXML 会不会有一定的价值，直到 xmlhttp.readyState 的 4的值。
Your HTTP request is asynchronous. xmlhttp.responseXML won't have some value until xmlhttp.readyState has the value of 4.
var url = "http://localhost/xml.php?type=xml";
var xmlhttp;
if (window.XMLHttpRequest) {
xmlhttp = new XMLHttpRequest();
}
else if (window.ActiveXObject) {
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
if (xmlhttp) {
xmlhttp.open("GET", url, true);
xmlhttp.setRequestHeader('Content-Type', 'text/xml');
xmlhttp.onreadystatechange = function () {
if (xmlhttp.readyState == 4) {
alert(xmlhttp.responseXML);
}
};
xmlhttp.send();
}
Additionaly，我不认为你需要的 setRequestHeader 行。的XML MIME类型所需的反应，而不是对请求。另外，请遵守良好的编码习惯（别忘了 VAR ，干，等。）
Additionaly, I don't think you need the setRequestHeader line. XML MIME type is required for response, not for request. Also, please respect good coding practices (don't forget var, DRY, etc.)