Javascript function to check for valid characters and invalid characters

If you want to validate a name feild with only alphabets. you can use below code to validate it.

<script  type="text/javascript"> 

if  (IsValidChars(document.getElementById( ).value.toLowerCase(), "abcdefghijklmnopqrstuvwxyz" )) {

alert("valid" );

}

else  {

alert("Invalid Characters" );

}

//Function to check the valid characters 

function  IsValidChars(Char_To_Be_Checked, Valid_Char) {

var  checkStr;

var  checkOK1;

var  allValid;

checkStr = Char_To_Be_Checked;

checkOK1 = Valid_Char;

var  allValid = true ;

for  (m = 0; m < checkStr.length; m++) {

ch = checkStr.charAt(m);

for  (n = 0; n < checkOK1.length; n++) {

if  (ch == checkOK1.charAt(n))

break ;

}

if  (n == checkOK1.length) {

allValid = false ;

break ;

}

}

return  allValid;

}

//Function to check the invalid characters 

function  IsInValidChars(Char_To_Be_Checked, InValid_Char) {

var  checkStr;

var  checkOK1;

var  allValid;

checkStr = Char_To_Be_Checked;

checkOK1 = InValid_Char;

var  allValid = true ;

for  (m = 0; m < checkStr.length; m++) {

ch = checkStr.charAt(m);

for  (n = 0; n < checkOK1.length; n++) {

if  (ch == checkOK1.charAt(n)) {

allValid = false ;

break ;

}

}

}

return  allValid;

}	

</script>