PHP and text fields

PHP and text fields are in the same PHP file with the following code:

How to assign a value to $ dsomething after entering the content in the text field,

Click the button to execute this code

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A normal button does not generate a submission action, and no form is displayed.
Then you need to use js to complete this task, and php cannot do it.

A normal button does not generate a submission action, and no form is displayed.
Then you need to use js to complete this task, and php cannot do it.
Do I have to jump to another page before using a form?

The form has the target attribute. you can point it to iframe and it will not jump.