JavaScript having trouble with using variables in innerHTML

Question

I'm having a problem with this code snippet

document.getElementById("hello").innerHTML = "<?php $query = 'select * from 
subcategory_ref where category_no = " + a +"'; 
$result=mysqli_query($dbc,$query); echo '<select>';
while($row = mysqli_fetch_array($result, MYSQLI_ASSOC)){
$id =$row['subcategory']; $name = $row['subcategory_name']; echo '<option> test </option>';};
echo '</select>'; ?>"

Var a is a number corresponding to a previous drop-down box. When alert(a) is used it alerts the value of var a but the innerHTML isn't reading it properly.

The reason I know there is a problem is if we replace the the 'a' in

subcategory_ref where category_no = " + a +"';

with

subcategory_ref where category_no = " + 1 +"';

The drop-down appears and is populated with the "test" option.

The value of var a is obtained like this

var a = document.getElementById("category").value;

Category being another drop-down box

However hard-coding a number inside the variable like this also doesn't work.

var a = 1;

Any ideas? We've been stuck on this for such a long time and it's unfortunately frustrating, any help would be greatly appreciated!

That `a` is still part of the php code, so it's being interpreted by php, not by JavaScript. This, of course, assumes that all of this is inside a php file. Also, little Bobby Tables would like to have a word with you. — Federico klez Culloca, Apr 04 '18 at 15:22
Is there anyway to make it so that 'a' can be interpreted by the PHP code? — Rafael Pangan, Apr 04 '18 at 15:24
Yes, don't do that in JavaScript. Pass that variable to a php script (via AJAX, for example) on the backend and do whatever you need to do from there. — Federico klez Culloca, Apr 04 '18 at 15:26
Also thank you for the answer! I used this algorithm before albeit a JSP version, which is why it worked correctly back then. — Rafael Pangan, Apr 04 '18 at 15:29

JavaScript having trouble with using variables in innerHTML

0 Answers0