Question

I have a php ternary operator as follows that does not work:

 var newLoginTxt = <?=$_SESSION['loginStatus']? 'Logged in' : 'Login'?>;
 alert("About to set the navbar's login text to: " + newLoginTxt);

No alert box appears at all.

However this does work:

var curLoginStatusSessionVar = <?=$_SESSION['loginStatus']? 'true' : 'false'?>;
alert("Testing: " + curLoginStatusSessionVar);

The alert box appears and says “Testing: false”

I have the following article seeming to say that the ternary operator in php CAN in fact return values other than ‘true’ or ‘false’:
http://davidwalsh.name/php-shorthand-if-else-ternary-operators

Okay, even more odd — in the code below, why does the first “Testing” alert box appear, then the 2nd “Testing” alert box NOT appear? It’s the exact same code:

      // THIS "Testing" ALERT BOX APPEARS FINE**
var curLoginStatusSessionVar = <?=$_SESSION['loginStatus']? 'true' : "false"?>;
alert("Testing: " + curLoginStatusSessionVar);


var newLoginTxt = <?=$_SESSION['loginStatus']? 'Logged in' : 'Login'?>;
alert("About to set the navbar's login text to: " + newLoginTxt);


    // THIS IDENTICAL "Testing" ALERT BOX NEVER APPEARS**
curLoginStatusSessionVar = <?=$_SESSION['loginStatus']? 'true' : 'false'?>;
alert("Testing" + curLoginStatusSessionVar);

Answer 1

Your problem is completely unrelated to the ternary expression: In JavaScript, like in modern php, strings must be encapsulated by quotes.

true and false happen to be JavaScript constants. Therefore, you want:

var newLoginTxt = "<?=$_SESSION['loginStatus']? 'Logged in' : 'Login'?>";
//                ^                                                    ^

Alternatively, and if the data is more complicated, use json_encode. For example, if you want to access the value of a php variable $title (which could contain quotes) in JavaScript:

<?php $title = '"Java"Script'; ?>
var title = <?php echo json_encode($title); ?>;
alert(title);