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javascript - AJAX PHP function onchange select box

I have a problem about which I am very confused. I have a select box with s dynamically generated using a mysqli query:

$result = mysqli_query($db, "SELECT * FROM `users` WHERE `user_id` > 0");
echo '<html><form name="contacts" method="post"><select name="contacts"><option value="Contact list" onchange="func()">Contact List</option>';
while($row = $result->fetch_assoc()){
    echo '<option value = '.$row['user_name'].'>'.$row['user_name'] . '</option>';
}
echo '</select></form>';

I am completely new to AJAX, but I need to use jquery and ajax to pass the this.value variable to a php variable for use in a later query.

Here is my script (most of which was found online):

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js">
$("#contacts").change(function() {
    //get the selected value
    var selectedValue = this.value;

    //make the ajax call
    $.ajax({
        url: 'function.php',
        type: 'POST',
        data: {option : selectedValue},
        success: function() {
            console.log("Data sent!");
        }
    });
});
</script>

Now, when I click a value in the select box, nothing happens. There are no warnings or errors, etc.

Please help me.

p.s. function.php does exist. It is just a simple echo for now (for testing purposes)

UPDATE: HERE IS FUNCION.PHP:

<?php
/*$val = $_REQUEST['selectedValue'];
echo $val;*/

function function(){
$val = $_REQUEST['selectedValue'];
echo $val;
}
?>

UPDATE: Thank you everyone for all your help. I have now got it to work in that the network section of chrome inspect shows the function.php being requested however I still don't get the echo (I used external .js files to get it to work). My J query function is also successful (the success function echoes into the console)

See Question&Answers more detail:os

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1 Answer

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by (71.8m points)

Your select box has no ID and you are watching the change event of $("#contacts").

Change:

echo '<html><form name="contacts" method="post"><select name="contacts"><option value="Contact list" onchange="func()">Contact List</option>';

to:

echo '<html><form name="contacts" method="post"><select name="contacts" id="contacts"><option value="Contact list">Contact List</option>';
                                                                        ^^^^^^^^^^^^^ here

You also only need one event handler, so I have removed the inline one which doesn't seem to do anything anyway.

Edit: If the select is created using ajax as well, you need event delegation:

$("body").on('change', '#contacts', function() {
   ^^^^ for example

Edit 2: Your variable is called $_REQUEST['option'] and not $_REQUEST['selectedValue']. You are also not calling your -badly named - function so you will not get any output from php except from an error like Parse error: syntax error, unexpected 'function' ....


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