I can't seem to pass a value to javascript function

Question

My code is like so

 function show_file(itemid) { document.getElementById("itemid").innerHTML = "Testing"; }

 <td id='$itemid' class='header-row'> MyText quote&nbsp;&nbsp; <button onclick='show_file($itemid)'> Button<i class='fa fa-angle-down'></i> </button> </td>

But I get this error "Cannot set property 'innerHTML' of null" so it seems the value of $itemid is not getting passed?

Answer 1

You should pass the actual function's parameter itemid not the string "itemid"

Change it from:

function show_file(itemid) {
  document.getElementById("itemid").innerHTML = "Testing";
}

To:

function show_file(itemid) {
  document.getElementById(itemid).innerHTML = "Testing";
}

Answer 2

That is because you gived a string in parameter to your getElementById function and not the itemid variable. Try this :

function show_file(itemid) {
  document.getElementById(itemid).innerHTML = "Testing";
}