Why Doesn\'t PHP Code Execute in the Browser Like JavaScript?

Understanding the Preprocessing Nature of PHP

Unlike JavaScript, which executes within a web browser, PHP is a preprocessing language that processes code before it reaches the browser. This difference can lead to confusion for newcomers.

Why PHP Doesn't Execute in a Browser

In the example provided:

<code class="html"><a href="<?php runCommand(); ?>"></a></code>

The runCommand() function won't execute when the button is clicked because PHP has already finished processing before the page is sent to the browser. This is because PHP is a server-side language, meaning it runs on the server before the page is displayed to the user.

Explaining the Preprocessing Concept

To understand how PHP works, it's important to grasp the concept of a preprocessor. PHP acts as a preprocessor in the following manner:

• It processes code before it is sent to the web browser.
• It typically generates HTML or other content that is then served to the browser.
• It does not execute any code within the browser itself.

Resources for Further Understanding

To redirect individuals to a comprehensive resource that explains PHP's preprocessing function, consider the following:

Wikipedia:

• Server-side scripting
• Client-side scripting

Additional Note:

As pointed out by Carl Smotricz, PHP does have some capabilities that allow it to run outside of a web browser. However, the question primarily addresses the context of Apache environments where a user requests a web page and expects an HTML response.

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