Below is function and it is not working. Maybe some small bug in the code which I am unable to identify.
<!DOCTYPE html>
<script>
function check(){
firstname=document.getelementById("firstname").value;
lastname=document.getelementById("lastname").value;
if(lastname==""){
alert('please enter lastname');
}
}
</script>
<form action="" method="post" onSubmit="check();">
<input type="text" id="firstname" name="firstname" ><br>
<input type="text" id="lastname" name="lastname" ><br>
<input type="submit" value="submit">
</form>
</body>
</html>
The bug in the code: case sensitive getelEmentById. Please below code and test it
function check(){
firstname=document.getElementById("firstname").value;
lastname=document.getElementById("lastname").value;
if(lastname==""){
alert('please enter lastname');
}
}
GetElementById, element with a capital E
JavaScript is case sensive.
TIP: use developer options in your browser. They usualy give an error message.
<!DOCTYPE html>
<script>
function check(){
firstname=document.getElementById("firstname").value;
lastname=document.getElementById("lastname").value;
if(lastname==""){
alert('please enter lastname');
}
}
</script>
<form action="" method="post" onSubmit="check();">
<input type="text" id="firstname" name="firstname" ><br>
<input type="text" id="lastname" name="lastname" ><br>
<input type="submit" value="submit">
</form>
</body>
</html>