基于PHP会话变量的JavaScript表单验证

Question

I have a login area of my site, and on login I set a session variable $_SESSION['logged_in'] = true .

Now I also have lots of forms and things where users can input comments. Obviously in my PHP validation I check the user is logged in simply using the session variable, but I want javascript validation too because I can make the user experience slicker that way.

$("body").on("click", ".submit", function(e){
    e.preventDefault();
    if (user == logged in){
        ...AJAX call to php file....
    }
})

So how do people generally do the bit where I check the user is logged in using javascript? ie if user == logged in

Answer 1

• You can of course check user permissions by AJAX (with JSON for example), but this will provide some additional latency.

• You can just write a value to global JS scope like this:

  if ( userIsLogged() ) { echo "<script>document.mysite.userlogged = true;</script>"; }

  then you can check document.mysite.userlogged variable.

• You can also set a cookie in PHP, wich can be obtained in JavaScript. To get cookies properly in JS see that: Javascript getCookie functions

• If you don't want to inject JS code, you can set some attribute like:

  <div id="comments" data-logged="<?php echo $isLogged; ?>"> ... </div>

  And get it by jQuery:

  if ( $("#comments").attr('data-logged') == 1 ) {

• you can provide logged/notlogged specific functionality for the whole page by generating JS file, like: <script type="text/javascript" src="http://yoursite.com/somefile.php"> and generate it in php dynamically, but be aware of caching !

Personally i would go to data-XXX attribute if tou want to personalize single block, and global JS variable if you check logged condition many times in JS.