passing php variable in javascript function - php

Question

I am new to php and javscript.I am working on some project of question and answer system.I want to send question id to javascript function.
here is my php code
<?php
if ($result->num_rows > 0)
{
$i = 1;
while($row = $result->fetch_assoc())
{
$p = $row["description"] ;
echo '<div onclick="myOverFunction(<?= $p ?>)" align="left" class="j" role="group" aria-label="..." > <button id = "btnl<?=$i?>" type="button" class="btn btn-default btn-xs btn-round" style="border-radius:10px;">';
echo $i;
echo '</button>';
echo '<p class="question" style ="display:inline; ">';
echo $p;
echo '</p>';
echo '</div>';
}
}
?>
My javacript function is:
<script>
function myOverFunction(x) {
document.getElementById("demo").innerHTML = x;
document.getElementById("btnl"+x).style.backgroundColor = "#d9534f";
}
</script>
my code does not working ..please help me ...

Answer 1

Your problem is:
echo '<div onclick="myOverFunction(<?= $p ?>)"
Change it to:
echo '<div onclick="myOverFunction('. $p .')".
Same goes for the other occurrences.
You can't echo from inside an echo
Your final echo should look like this:
echo '<div onclick="myOverFunction(\''. $p .'\')" align="left" class="j" role="group" aria-label="..." > <button id = "btnl'.$i.'" type="button" class="btn btn-default btn-xs btn-round" style="border-radius:10px;">';
Note: If $p is a string, it needs quotes. And quotes inside quotes need escaping

Answer 2

You are breaking this line by trying to re-open php tags within the echo:
echo '<div onclick="myOverFunction(<?= $p ?>)" align="left" class="j" role="group" aria-label="..." > <button id = "btnl<?=$i?>" type="button" class="btn btn-default btn-xs btn-round" style="border-radius:10px;">';
Try this:
echo '<div onclick="myOverFunction('.$p.')" align="left" class="j" role="group" aria-label="..." > <button id = "btnl'.$i.'" type="button" class="btn btn-default btn-xs btn-round" style="border-radius:10px;">';