Php调用javascript函数

I can do that? Im trying to call a javascript function after conditional php "if"

<script type="text\javascript">
functioncall = (function(id){
   alert(id);
});
</script>

<?php
if(isset($_get['id']){
   echo "<script>functioncall({$_get['id']});</script>";
}
?>

Use $_GET instead of $_get in php condition, I have corrected some of the errors like script tag script type, and PHP $_GET

    <script type="text/javascript">         
        functioncall = (function(id){
               alert(id);
        });
   </script>

 <?php
    if(isset($_GET['id'])){
       echo "<script>functioncall('{$_GET['id']}');</script>";
    }
 ?>

Or just using JS ?

function getQueryVariable(variable) {
       var query = window.location.search.substring(1);
       var vars = query.split("&");
       for (var i=0;i<vars.length;i++) {
               var pair = vars[i].split("=");
               if(pair[0] == variable){return pair[1];}
       }
       return(false);
}

And do like...

var id = getQueryVariable('id');
if(id) {
    alert(id);
}

Credit : http://css-tricks.com/snippets/javascript/get-url-variables/

As Quentin said you are exposed to XSS attacks. Don't ever put anything into your page from GET variables (url variables) - 'id' in your case.

Anyways, if you want to call a function based on a php condition, you can do something like this:

<script type="text\javascript">
functioncall = (function(id){
   alert(id);
});
</script>

<?php
if(condition-goes-here){
?>
<script type="text/javascript">
   functioncall(<?php echo 'Put in your php data' ?>);
</script>
<?php } ?>

I haven't checked it, hope it should work. If your condition returns false, your function call will not be put into your page.

It's not a good practice though.