fmpq.com
源代码：
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<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Fmpq教程(fmpq.com)</title> <script> function displayResult(){ alert(document.getElementById("mySelect").length); } </script> </head> <body> <form> <select id="mySelect"> <option>Apple</option> <option>Pear</option> <option>Banana</option> <option>Orange</option> </select> </form> <button type="button" onclick="displayResult()">下拉列表中有多少选项?</button> </body> </html>
运行结果