How to dynamically change the readOnly property of input without relying on JavaScript using PHP?

Get rid of JavaScript and dynamically adjust the readOnly property of input with PHP

In web form development, it is very common to dynamically control readOnly property of the input box. Many developers believe that this can only be achieved through JavaScript, but it is not. This article will demonstrate how to achieve this using PHP only without any JavaScript code.

Some users tried to dynamically modify the readOnly attribute using the following PHP code, but the results were not good:

<input type="text" value="<?php echo isset($_GET['username']) ? $_GET['username'] : ''; ?>">

The problem is that readOnly property is not a simple boolean switch. As long as readOnly property exists, regardless of its value is true or false , the input box will be read-only.

The correct PHP code should dynamically add or remove readOnly property itself:

<input type="text" value="<?php echo isset($_GET['username']) ? $_GET['username'] : ''; ?>" if echo>>

Decide whether to output readonly attribute by adding conditional judgment ( /*此处添加你的条件判断*/ ). If the condition is true, add the readonly property to make the input box read-only; otherwise, the property is not added and the input box remains editable. This cleverly uses PHP to achieve the purpose of dynamically controlling readOnly attribute.

This method completely avoids the participation of JavaScript, making it more concise and efficient.

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