Question

I’m trying to validate my values for alphabets and numberic as well as checking from database. I have created a function of validation and declaring my onclick button with validation function.

Function:

<script>
function validate()
{
var StudentID= document.getElementById('StudentID').value;
var StudentName = document.getElementById('StudentName').value;
    var StudentAdd = document.getElementById('StudentAdd').value;

    if(StudentID.length ==0 || StudentName.length ==0)
{
    alert("Please do not leave any blanks");
    return false;
}
else
{
            if(isNumeric(StudentID))
            { alert("correct") }
            else { alert("Numbers only!"); return false;}

    alert("Correct correct");   
}
    return true;
}
</script>

Sample Form:

<form id="Student" name="Student" method="post" action="nextpage.php">
<input name="StudentID" type="text" id="StudentID" value="<?php echo $StudentID?>"/>
<input name="StudentName" type="text" id="StudentName" value="<?php echo $StudentName?>"/>
<input name="StudentAdd" type="text" id="StudentAdd" value="<?php echo $StudentAdd?>"/>
<input type="submit" name="submit" value="Submit" onclick="return validate();"/>
</form>

I have already declared return validate function instead of calling my nextpage.php. But nothing popup for any alert. Kindly advise.
Thanks

Answer 1

Try including your scripts after the body tag to make sure it only references elements after it has already been loaded. Then put return true inside the else statement.

function validate()
{
var StudentID= document.getElementById('StudentID').value;
var StudentName = document.getElementById('StudentName').value;
    var StudentAdd = document.getElementById('StudentAdd').value;

    if(StudentID.length ==0 || StudentName.length ==0)
{
    alert("Please do not leave any blanks");
    return false;
}
else
{
            if(isNumeric(StudentID))
            { alert("correct") }
            else { alert("Numbers only!"); return false;}

    alert("Correct correct");   
   return true;
}

}