How to get a PHP variable in JavaScript in this case?

Question

in following case I want my script to running post.php. That works fine. But while running the post.php file, in it a variable should be created with content "1". And I want to get the variable in my javascript back. So there are two files:

part of index.php

<script type="text/javascript">
        function post()
        {
            var message = $('#message').val();
            $.post('post.php', {postmessage:message},
            function(data)
            {
                $('#result').html(data);
            });
        }
</script>

and then I have the post.php where the variable with content "1" should be created.. Then I want to get back it in index.php in the script. How can I do this?

Why do I want to do this? When in post.php a variable with content "1" will be created, >>I think it has to be a $_POST variable?<< then I want to clear my form field because the action in post.php went successfully.

It can be either post or get, doesn't really matter. You can send more data via post (and even more by fedex). Also note that $.post() is a shorthand form of $.ajax(), so learn the longer form first. — cssyphus
– cssyphus, Commented Dec 2, 2018 at 14:38

Jakub Hubert · Accepted Answer · 2018-12-02 18:50:04Z

1

One of the ways to do so is to return JSON encoded variable from your post.php file. Response from your file is in the data variable in the callback function parameter of your $.post method after the server responds.

Take care, that you need to also parse this data from JSON into plain JS on frontend side so you can work with that. The code may look like this:

Frontend side - index.php:

<script type="text/javascript">
    function post()
    {
        var message = $('#message').val();
        $.post('post.php', {postmessage:message},
        function(data)
        {
            var parsedData = JSON.parse(data);
            $('#result').html(parsedData);
        });
    }
</script>

Backend side - post.php:

<?php
// get sent variable
$message = $_POST['postmessage'];

// do what you need to do with that

// consider your processing resulting in success
$success = true;

echo json_encode($success);
?>

edited Dec 2, 2018 at 18:50

answered Dec 2, 2018 at 14:19

Jakub Hubert

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2 Comments

cssyphus Over a year ago

@kadnick The key part to this answer is to use echo - that is how you send the response from the PHP side to the javascript/ajax side.

user5125586 Over a year ago

To safe load on your server, consider calling "exit;" after the echo or using die instead of echo e.g. die(json_encode($success));

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