<html><body><div id="demo"><h1>XMLHttpRequest 对象</h1><button type="button" onclick="loadDoc()">更改内容</button></div><script>function loadDoc() { const xhttp = new XMLHttpRequest(); xhttp.onload = function() { document.getElementById("demo").innerHTML = this.responseText; } xhttp.open("GET", "/demo/js/ajax_info.txt"); xhttp.send();}</script></body></html>