W3School TIY Editor
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<!DOCTYPE html> <html> <body> <select id="mySelect" autofocus> <option value="volvo">沃尔沃</option> <option value="saab">萨博</option> <option value="porsche">保时捷</option> <option value="audi">奥迪</option> </select> <p>单击按钮可查看下拉列表是否在页面加载时自动获得焦点。</p> <button onclick="myFunction()">试一试</button> <p id="demo"></p> <script> function myFunction() { var x = document.getElementById("mySelect").autofocus; document.getElementById("demo").innerHTML = x; } </script> </body> </html>