Php script error with on click event

Question

I am using wordpress as my cms and I am devloping a voting system. I want this code to run only on click event but it runs on every page load

How can i only make it run on click even

<script>
function addvote(){
 alert("<?PHP hello(); ?>");
}
 < /script>

 <?PHP
FUNCTION hello(){
   $postid="79";
   $current_votes = get_post_meta($postid, "votes", true);
$new_votes = intval($current_votes) - 1;
update_post_meta($postid, "votes", $new_votes);
$return = $new_votes>1 ? $new_votes." votes" : $new_votes." vote";
echo $return;
 }

?>

<button onclick="addvote()">Vote Now</button>

do you want to addvote() run on each click or hello() function? hello() function will run on each page request — Mustafa Shujaie
– Mustafa Shujaie, Commented Jan 19, 2013 at 20:42
need to explain what you expect your code to do...in detail, and behavior you want. php and javascript run in completely different environments — charlietfl
– charlietfl, Commented Jan 19, 2013 at 20:43
I only expect the code to run on click event But instead the code runs on page request .. mean runs on each page load — Vaibhav Bhanushali
– Vaibhav Bhanushali, Commented Jan 19, 2013 at 20:45

lethal-guitar · Accepted Answer · 2013-01-19 20:47:52Z

3

You cannot invoke PHP from JavaScript like that. You need AJAX: http://en.wikipedia.org/wiki/Ajax

Also, use unobtrusive JavaScript - attach event handlers in your Script code, not in the HTML. Basic example how to implement what you probably want, using jQuery:

// In your HTML page:
<scipt type="text/javascript">
    $(document).ready(function() {
        $('button').click(function() {
            $.get("/hello.php", function(data) {
                alert(data);
            });
        });
    });
</script>

// In hello.php:
<?php
function hello() {
    // ...
    echo $return;
}

hello();
?>

You need to understand the distinction between server- and client-side processing. All your PHP code is executed on the server on each page request. The results are then sent to your browser, which displays them. Now there can be JavaScript code in your page, which is executed by the browser after the page is loaded. In order to invoke PHP code on a button click (or similar), this client-side code needs to make a new HTTP request to the server - this is what AJAX is for. This new request will trigger the execution of another PHP script. The results are transferred back to the JavaScript function after it finishes, and can then be used to do something, like adding additional content to your page.

edited Jan 19, 2013 at 20:47

answered Jan 19, 2013 at 20:42

lethal-guitar

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3 Comments

Vaibhav Bhanushali Over a year ago

can i put in my themes functions.php i mean that function hello putting it in theme funcions.php will give it gloabal acces at my site

lethal-guitar Over a year ago

I have no experience with WordPress, so sorry - I don't know.

Vaibhav Bhanushali Over a year ago

returning value of 0 using url there $.get("wp-content/themes/9GAG/hello.php"

Mustafa Shujaie · Accepted Answer · 2013-01-19 20:50:00Z

0

when you request this page PHP parser will encounter with hello() function, and it will run it and therefore it will print the return value of hello() function in the javascript alert() function, so the output wil be, (assuming return value be 1):

<script>
    alert('1');
</script>

as @lethal-guitar mentioned you need to call the hello() function with an AJAX request.

answered Jan 19, 2013 at 20:50

Mustafa Shujaie

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