textbox null php

by Jayme207

HTML

<!DOCTYPE html>
<html>
<body>
<form action="/action_page.php">
  <label for="fname">Fname:</label>
  <input type="text" id="fname" name="fname"><br><br>
  <label for="lname">Lname:</label>
  <input type="text" id="lname" name="lname" disabled><br><br>
  <input type="submit" value="Submit">
</form>

<script>
const fname = document.querySelector(".fname");
const lname = document.querySelector(".lname");

lname.readonly = true;
fname.addEventListener("keyup", () => {
if(fname.value.length >0)
{
lname.readonly = false;
}else
{
lname.readonly = true;
}

})



</script>

</body>
</html>