How do I get button's ID from a list of buttons?

Question

I haven't worked much with php and javascript and was hoping to get some help. I want to be able to detect which button was clicked exactly. I'm creating one button per row but I don't know how to figure out what row the click was made in. This is what I have so far...

    # Get all the table data from the database
$getData = mysqli_query($conn, "SELECT * FROM `query_table`") or die ("Error occured while selecting!");

// echo '<form method="post" action="index.php">';
echo '<table border="1">';

echo '<tr>';
echo '<td>Questions</td>';
echo '<td>Likes</td>';
echo '<td></td>';
echo '</tr>';

# Loop through each row and print out the question
while ($row = mysqli_fetch_array($getData)) {
    echo '<tr>';
        echo '<td>';
            echo $row['Question'];
        echo '</td>';

        echo '<td>';
            echo $row['Likes'];
        echo '</td>';

        echo '<td>';
        ?>

            <input type="button" id="myButton" value="Like" onclick="myFunc(<?=$row['ID']?>)" />

        <?php
        echo '</td>';
    echo '</tr>';
}

echo '</table>';
// echo '</form>';
echo '<p id="text"></p>';

mysqli_close($conn);
?>

<script type="text/javascript">
function myFunc(id) {
    document.getElementById("text").innerHTML = id;
}
</script>

So far this prints out the row id where the button was clicked, but I don't suppose I can assign that parameter value directly to a php variable that I can then use for mysql queries. How is stuff like this normally done, please help.

so, the button is only one and need to check if LIKE and Question is clicked? — Joe Kdw, Mar 09 '15 at 03:47
unrelated: `id`s on objects must be unique. you are giving every button the same id with `id="myButton"` - you should either not give them an id, or make sure they are unique (eg `id="myButton_= i ?>"` where i is an incrementing counter of some sort) — Taryn East, Mar 09 '15 at 03:53
possible duplicate of [Javascript onclick event handler - how do I get the reference to the clicked item?](http://stackoverflow.com/questions/7846268/javascript-onclick-event-handler-how-do-i-get-the-reference-to-the-clicked-ite) — RandomSeed, Mar 09 '15 at 11:58
To "assign the value to a PHP variable" you would need to make another call to the server, either via AJAX or a standard GET/POST request. See http://stackoverflow.com/questions/13840429/what-is-the-difference-between-client-side-and-server-side-programming — daiscog, Aug 10 '15 at 17:43

score 1 · Answer 1 · answered Aug 10 '15 at 17:24

<input type="button" data-id="<?=$row['ID']?>" value="Like" onclick="myFunc(this)">

and

<script type="text/javascript">
function myFunc(button) {
    document.getElementById("text").innerHTML = button.getAttribute('data-id');
}
</script>

In JavaScript the token "this" refers to the context in which the code is running which in this case is the button. Store custom data in attributes prefixed with data- to ensure they are not disturbed - standard practise.

How do I get button's ID from a list of buttons?

1 Answers1