​x
 
<!DOCTYPE html>
<html>
<body>
​
<h1>XMLHttpRequest 对象</h1>
​
<p>getAllResponseHeaders() 函数返回资源的所有头信息，如长度，服务器类型，内容类型，最后修改等：</p>
​
<p id="demo"></p>
​
<script>
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
  if (this.readyState == 4 && this.status == 200) {
    document.getElementById("demo").innerHTML =
    this.getAllResponseHeaders();
  }
};
xhttp.open("GET", "/demo/js/ajax_info.txt", true);
xhttp.send();
</script>
​
</body>
</html>
​