W3School TIY Editor
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<!DOCTYPE html> <html> <body> <p>请从列表中选择一辆新车。</p> <select id="mySelect" onchange="myFunction()"> <option value="Audi">Audi</option> <option value="BMW">BMW</option> <option value="Mercedes">Mercedes</option> <option value="Volvo">Volvo</option> </select> <p>当您选择一辆新车时，会触发一个函数，输出所选汽车的值。</p> <p id="demo"></p> <script> function myFunction() { var x = document.getElementById("mySelect").value; document.getElementById("demo").innerHTML = "You selected: " + x; } </script> </body> </html>