CODEWITHSUNDEEP
phpjavascripthtmlmysqlcss
Thomas John
Thomas John

Reputation: 1899

order of execution in web environment

what is the order of execution in web ? PHP, HTML, Javascript, css and mysql are the items to execute

Upvotes: 3

Views: 5850

Answers (7)

Alex
Alex

Reputation: 66032

Order of execution (When you first visit a page):

Server-side first, then client-side.

Web server handles request, then begins execution of server-side scripts.

PHP is server-side, so it'll execute first. Your using PHP to execute mysql queries and get data out of tables, correct? So during the execution of your PHP script(s), your mysql queries will execute. Then, when your PHP has finished executing, your client-side elements (HTML, Javascript, css) will get executed/be interpreted.

Upvotes: 1

Ming-Tang
Ming-Tang

Reputation: 17661

The order is like this:

  • Browser - send request
  • Server - execute PHP script
  • Server - send output to browser
  • Browser - read output and execute JavaScript

Here is an example:

  • Browser: requesting page /index.php

  • Server: execute index.php file on the server

    <?php echo "Hello, world!;"; ?> <script>alert("hello!")</script>

  • Server: respond the output

  • Browser: parse the output
  • Browser: <script> detected, alert("hello!")

Upvotes: 6

jcomeau_ictx
jcomeau_ictx

Reputation: 38492

The answer is a little complicated, and part of it depends on your webserver. Part of the answer, in Apache, is in your DirectoryIndex setting. If you have several possible files, index.html, index.cgi, index.php, etc., this will determine which is used:


DirectoryIndex index.cgi index.php index.shtml index.html

ISS has a similar mechanism, but it's been years since I messed with it.

HTML and CSS are interpreted by the browser (client-side). Javascript is generally run on the client side, but some servers allow for server-side execution as well.

Mysql is run on the server, generally in response to a php or cgi script's query.

Upvotes: 1

Quentin
Quentin

Reputation: 944430

Anything server side will run, then anything client side will run (in the order it appears, although note that running some bits of code just sets up an event handler that contains code that will run when the event actually happens)

Upvotes: 0

S&#233;bastien VINCENT
S&#233;bastien VINCENT

Reputation: 1106

I can only recommand you a lot to view this talk by Steve Souders on JSConf : http://jsconfeu.blip.tv/file/3060565/

He talked about to best practices to optimise loading of your page on client side.

On the server side, you should know PHP stop execution until it get response from MySQL.

Upvotes: 0

Matt Briggs
Matt Briggs

Reputation: 42248

User makes a request -> handled by your web server (probably apache) -> handed off to php -> php builds html using mysql and returns it -> html is interpreted, and references css -> javascript executes on the client

Upvotes: 0

Vic
Vic

Reputation: 1346

That depends on what order everything is on the page top to bottom.

Upvotes: 0

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