Giá trị trong HTML được chọn là gì?

nội dung

Mã ví dụ

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Chọn loài chim hồng hạc yêu thích của bạn

Gửi dữ liệu tùy chọn trong biểu mẫu

Khi bạn xác định một biểu mẫu, bạn sẽ sử dụng phần tử để tạo các tùy chọn có thể chọn khác nhau. Văn bản bạn viết giữa và là văn bản mà khách truy cập sẽ thấy

Nội dung của thuộc tính value cho được gửi dưới dạng phản hồi cho biểu mẫu, vì vậy đây là nội dung sẽ được gửi tới người nhận email hoặc gửi tới cơ sở dữ liệu

Người dùng không nhìn thấy giá trị của nó và chỉ nhìn thấy văn bản giữa và

Điều gì xảy ra nếu không có giá trị?

Nếu bạn không chỉ định một value cho tùy chọn, thì văn bản giữa và sẽ được gửi thay thế

Trong một số trường hợp – chẳng hạn như biểu mẫu email – đây có thể là hành vi hợp lệ. Tuy nhiên, điều này có thể dẫn đến dữ liệu dạng dài không hoạt động tốt với các trường cơ sở dữ liệu hoặc tuân theo các giới hạn về độ dài tối đa

Trong mọi trường hợp, tốt nhất là chỉ định value

Claire Broadley

Claire là nhà văn, biên tập viên kỹ thuật dày dạn kinh nghiệm và người đam mê HTML. Cô ấy viết cho HTML. com và điều hành một công ty nội dung, Red Robot Media

Trong bài viết này, chúng ta sẽ tìm hiểu về cách đặt giá trị mặc định cho phần tử select trong HTML và cũng sẽ hiểu cách triển khai chúng thông qua các ví dụ

Thẻ select trong HTML được sử dụng để tạo danh sách thả xuống gồm các tùy chọn có thể được chọn. Thẻ tùy chọn chứa giá trị sẽ được sử dụng khi được chọn. Giá trị mặc định của phần tử được chọn có thể được đặt bằng cách sử dụng thuộc tính 'đã chọn' trên tùy chọn bắt buộc. Đây là một thuộc tính boolean. Tùy chọn có thuộc tính 'đã chọn' sẽ được hiển thị theo mặc định trong danh sách thả xuống. Chúng tôi thậm chí có thể đặt thuộc tính đã chọn sau khi trang được tải với sự trợ giúp của Javascript

cú pháp

Option Name

ví dụ 1. Ví dụ này minh họa việc sử dụng thuộc tính đã chọn bằng cách chỉ định tùy chọn được chọn trước sẽ được hiển thị đầu tiên từ danh sách thả xuống

HTML

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

đầu ra

thuộc tính đã chọn

ví dụ 2. Điều này cũng có thể được sử dụng để thêm các thông báo như 'Chọn một tùy chọn' trong danh sách. Tùy chọn này sẽ có thuộc tính ẩn và bị vô hiệu hóa ngoài thuộc tính đã chọn

HTML

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

Select your favorite species of flamingo.


          American flamingo
          Greater flamingo
          Lesser flamingo
          Andean flamingo
          Chilean flamingo
          James's flamingo

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

HTML optimum Attribute Demo
Select your favourite subject:

đầu ra

Đã tắt thuộc tính đã chọn

HTML là nền tảng của các trang web, được sử dụng để phát triển trang web bằng cách cấu trúc các trang web và ứng dụng web. Bạn có thể học HTML từ đầu bằng cách làm theo Hướng dẫn HTML và Ví dụ về HTML này

Làm cách nào để đặt giá trị trong HTML được chọn?

Giá trị trong HTML là gì?

Giá trị chọn là gì?

Chúng tôi có thể sử dụng thuộc tính giá trị trong thẻ chọn không?