Detailed explanation of hidden fields in html

Hidden fields are actually tags of hidden forms in the HTML web page code. Value sets can be written in them, but they will not be displayed on the surface of the web page. The specific form is .
It can be seen that type="hidden" means that it is a hidden domain. Some value sets are saved in value and can be obtained and modified through name, id or other methods.

It has many functions, such as: value passing and security are all used. When you are missing any value, you can hide the value passing on the page and the page will not be displayed. The function is the same as other inputs, except that the user cannot see it directly and is used to assist the server in completing some actions.


Hidden fields are invisible to users on the page. The purpose of inserting hidden fields into the form is to collect or send information so that it can be used by the program that processes the form. Here is a detailed introduction Here's how this hidden field is used in practice:
Basic syntax:

<input type="hidden" name="field＿name" value="value">

Function:

1 Hidden fields are visible to users on the page Invisible, the purpose of inserting hidden fields into a form is to collect or send information so that it can be used by the program that processes the form. When the viewer clicks the send button to send the form, the hidden field information is also sent to the server.

2 Sometimes we need to give the user information to determine the user's identity when submitting the form, such as session key, etc. Of course, these things can also be implemented using cookies, but it is much simpler to use hidden fields. And there will be no worries about browsers not supporting it and users disabling cookies.

3 Sometimes there are multiple submit buttons in a form. How can the program distinguish which button the user pressed to submit? We can write a hidden field, and then add onclick="document.form.command.value="xx"" to each button. Then after we receive the data, we first check the value of the command and we will know which one the user clicked. button to submit.

4 Sometimes there are multiple forms in a web page. We know that multiple forms cannot be submitted at the same time, but sometimes these forms do interact with each other, so we can add hidden forms in the form. domain to connect them.

5 JavaScript does not support global variables, but sometimes we must use global variables. We can store the value in the hidden field first, and its value will not be lost.

6 There is another example. For example, pressing a button will pop up four small windows. When one of the small windows is clicked, the other three will automatically close. However, IE does not support small windows calling each other, so you can only write a hidden field in the parent window. When the small window sees that the value of the hidden field is close, it will close itself.

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