Question

I have a texbox that is like this:

<input type="text" size="30" name="form[id]" id="form_id">

I need a JavaScript function that will validate:

1. No Spaces allowed.
2. Only numbers, letters, dashes(-) and underscores(_) allowed and no other special character allowed.
3. Shouldn’t be empty

On Submit when the user’s input is violating a validation. An alert message should be displayed.

Answer 1

Here is the javascript

<script type="text/javascript">

function NoSpecialChars(){
    var element=document.getElementById('form_id');
    var specialchars= "!@#$%^&*()+=[]\\\';,./{}|\":<>?";
    if(element.value.length==0){
        alert('Enter some text');
        return false;
    }
    for (var i = 0; i < element.value.length; i++) {
        if (specialchars.indexOf(document.formname.fieldname.value.charAt(i)) != -1) {
            alert ("Those are not allowed.");
            return false;
        }
    }
    return true;
}
</script>

You need to subscribe the onclientclick event of the textbox.

<input type="text" size="30" name="form[id]" id="form_id" onclientclick="return NoSpecialChars();">

Hope it helps