Running JavaScript in PHP file

Question

I made a simple login using JavaScript, but record the username in a PHP session.It's a simple web chat, so I want when the chat page is loaded the user to be forced to pick an username, but after that I want to store that info ina a PHP session and if the page is reloaded for some reason to do a check if $_SESSION['UserName'] is empty and if it's not to stop the script from executing again.I put my login JS in <body onload..> and the code looks like this:

<body onload = "showUser(), showChat(), <?php if ($_SESSION['UserName']==""){
{
  Login();
}?>">

I'm just learning now, so I gues I have some newb mistakes, like I'm almost sure that I'm not calling the Login() function right (it's JS function), but that's my strating point.Could anyone explain to me, how should I do the check properly and add the JS function in my PHP code?

P.S And I don't know if this really matter but if I remove the PHP code and leave liek this:

<body onload = "showUser(), showChat(),Login()">

My script is executed properly and I get everything that should be shown when the page is loaded, but when I add the PHP script and try to load the page I get blank page.I really wonder what's the reason for this too?

en.wikipedia.org/wiki/Unobtrusive_Javascript - please read.

ThiefMaster
– ThiefMaster

2011-06-07 06:21:46 +00:00
Commented Jun 7, 2011 at 6:21 — ThiefMaster
– ThiefMaster, Commented Jun 7, 2011 at 6:21

Jagadeesan · Accepted Answer · 2011-06-07 06:31:37Z

4

You cant call a js function from php. instead we have to print the js function as string in php so it will be executed as js along the html.

<body onload = "showUser(); showChat(); <?php if ($_SESSION['UserName']==""){ echo 'Login();'; }?>">

To Write efficient php code:

<body onload = "showUser(); showChat(); <?php echo (($_SESSION['UserName']=='')?'Login();':''); ?>">

You get blank page because of fatal error. which is occurred due to the javascript function you called in php (ERROR: Undefined function login() ).

edited Jun 7, 2011 at 6:31

answered Jun 7, 2011 at 6:14

Jagadeesan

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Comments

Michael Robinson · Accepted Answer · 2011-06-07 06:20:17Z

2

You must echo the text Login(); from PHP - PHP does not execute Javascript, but you can use it to control which Javascript functions are called.

<body onload="showUser(), showChat(), <?php 
    if(isset(!$_SESSION['UserName']) || $_SESSION['UserName'] == ""){ 
        echo 'Login();';
     }?>">

You are effectively using PHP to create two different body tags - one for logged in users, and one for others.

Side note: it's good practice to check that an array item exists before attempting to access it: isset($_SESSION['UserName']) || $_SESSION['UserName'] checks first if $_SESSION['UserName'] has been set, then checks if it has been set to something other than an empty string.

edited Jun 7, 2011 at 6:20

answered Jun 7, 2011 at 6:14

Michael Robinson

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4 Comments

Leron Over a year ago

Thanks all try it now, just to make it clear, I put all the info in DB, which i proseed in another .PHP file and if the user dosen't provide any text I just assign 'anonymos' to $_SESSION['UserName']

Jagadeesan Over a year ago

if we check isset in this case, it alows the logged in users inside the condition. use ! before isset to reverse the function.

Leron Over a year ago

Now I see how to add my JS in PHP script, but still can't prevent the Login() function from executin when the page is reloaded

Michael Robinson Over a year ago

@Leron, add the ! before the first $_SESSION, I had accidentally missed it out, sorry!

Nick Craver · Accepted Answer · 2011-06-16 13:58:32Z

0

You can simply call this as:

<?php 
    if($_SESSION['UserName'] == ""){ 
?>
<body onload="showUser(), showChat()">
<?php
    }
    else
    {
?>
<body onload="showUser(), showChat(), Login();">
<?php
    }
?>

edited Jun 16, 2011 at 13:58

Nick Craver

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answered Jun 7, 2011 at 6:19

praneeth

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3 Comments

Leron Over a year ago

Parse error: syntax error, unexpected '<' in C:\Program Files\webPHP\xampp\htdocs\MyChat\chat1.php on line 75

Leron Over a year ago

Ops, sry, I've been trying some other thing, could you post the entire code again?Thanks

praneeth Over a year ago

U can simply call this as <?php if($_SESSION['UserName'] == ""){ ?> <body onload="showUser(), showChat()"> <?php } else { ?> <body onload="showUser(), showChat(), Login();"> <?php } ?>

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