Pass value from php to javascript

Question

Hello Im trying to pass value stored in php to javascript code.

I try to pass the value in $_SESSION[user]

If I have this script in my header:

<script>

var user = ? //How to pass the value?

</script>

In my buttons I do something like this:

onclick="foo('<?php session_start(); echo $_SESSION[user];?>')

But how do I pass it without the user click?

Thanks for helping

EDIT

My JS function located in other file and I reference them by this code in my header:

<script src="class_functions"></script>

How do I pass the same parameter to the other file?

possible duplicate of [Passing a PHP variable to JavaScript](http://stackoverflow.com/questions/16148772/passing-a-php-variable-to-javascript) — Floris, Mar 23 '14 at 14:05

score 5 · Answer 1 · answered Mar 23 '14 at 13:53

5

Just echo the PHP value out like you would any content:

<script>
    var user = '<?php echo $_SESSION[user]; ?>';
</script>

JavaScript is just client-side code like HTML is.

answered Mar 23 '14 at 13:53

John Conde

217,595
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Or the even shorter ` var user = '= $_SESSION[user]; ?>';` – Floris Mar 23 '14 at 13:56
Yep. Be careful though. Newbies will tell you to never use short tags! – John Conde Mar 23 '14 at 13:57
Its working thanks. But now i have another problem please see my edit, thanks. – dasdasd Mar 23 '14 at 14:00
Would be a good idea to check for the session index to be set though. – developers-have-no-vacation Mar 23 '14 at 14:01
@geekynotsilly That would only be necessary if this was not behind some sort of login. If you've authenticated the user then you can be sure that information exists. – John Conde Mar 23 '14 at 14:02
Guess *user* normally should be quoted. (PHP-code). – user13500 Mar 23 '14 at 18:42

score 4 · Answer 2 · answered Mar 23 '14 at 13:55

4

If you're PHP script is rendering the page, I would go with the script tag approach.

<head>
   <script type="text/javascript">
       var user = '<?php echo $_SESSION["user"]; ?>';
   </script>
</head>
<body>
</body>

answered Mar 23 '14 at 13:55

thetrompf

430
3
11

Floris · Accepted Answer · 2014-03-23T16:06:46.030

Now that you have added an additional factor to your question, it is a little bit more interesting. If you need to set a variable when the functions that use this variable are located in a different file, then you need to decide the scope of the variable you are passing. There are several options; I will just list two:

Global scope. That is, the variable will be "known" to the other functions because of where it it located. You want to be careful of this, but if that's your approach you can use any of the answers given, e.g.
```
<script>
var x = '<?= $_SESSION["user"];>';
</script>
```
Local scope. Now you will need to include a function in class_functions that sets the variable. You might end up with something like
```
<script>
  set_user('<?= $_SESSION["user"];>');
</script>
```

Where the set_user() function is defined in your other file, and ensures that the variable is available to the other functions with the correct scope.

I would prefer using method 2 - it is much cleaner.

Thanks. I used the set_user :) – dasdasd Mar 23 '14 at 15:41 — dasdasd, Mar 23 '14 at 15:41

Al.G. · Answer 4 · 2014-03-23T14:05:23.193

1

I think this is better:

<script>
    var user = '<?php echo htmlentities($_SESSION["user"]); ?>';
</script>

Because if there are quotes $_SESSION['user'], you will get an error. For example if you have:

$_SESSION['user'] = "something with 'quotes'";

the js would like so:

var user = 'something with 'quotes'';

Which is incorrect.

edited Mar 23 '14 at 14:05

answered Mar 23 '14 at 13:58

Al.G.

4,327
6
31
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You shouldn't use addslashes(). You should use htmlentities(). – John Conde Mar 23 '14 at 14:00
You should avoid short_open tags for your example because it is configuration depended if it works or not. And I agree use htmlenitites() – thetrompf Mar 23 '14 at 14:02

Manjeet · Answer 5 · 2014-03-23T15:01:00.927

0

You Can use Jquery ,if you want it to happen automatically.

just Use the following code inside your tags

$(document).ready(function()
{
    var user= <? echo $_SESSION['user']?>;
    //Code Goes here......

});

Hope that solves Your Problem

Note:This can be one of the many possible solutions

edited Mar 23 '14 at 15:01

answered Mar 23 '14 at 14:06

Manjeet

37
5

jQuery *is* JavaScript. If one include jQuery only to add an onload event, for which one do not need jQuery, one have to seriously rethink the approach. – user13500 Mar 23 '14 at 14:09
I know jquery is JAVASCRIPT, the question was about to pass PHP value to JavaScript without buttons.......and this can be one of the ways to pass the data – Manjeet Mar 23 '14 at 14:29
You do not need to wait for DOM to set a JavaScript variable. – user13500 Mar 23 '14 at 14:41
Unless *user* is a number or some literal like *false* or *null* etc., it will also break the script. – user13500 Mar 23 '14 at 15:34
You can check for null or other conditions using if statement – Manjeet Mar 23 '14 at 15:48
So *user* should be *null*, *false* or the like. (Or a possible earlier global variable)? Hint: What if `$_SESSION['user']` is *John Wayne*? What if it is *usr123* and there is no global variable *usr123*? – user13500 Mar 23 '14 at 18:10

Pass value from php to javascript

5 Answers5