源代码
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>编程字典</title> </head> <body> <select> <optgroup label="瑞典车"> <option value="volvo">Volvo</option> <option value="saab">Saab</option> </optgroup> <optgroup label="德国车"> <option value="mercedes">Mercedes</option> <option value="audi">Audi</option> </optgroup> </select> </body> </html>
运行结果