alphanumeric valdations using javascript regular expressions

Below is the code which can be used to validate alphabetic charecters using javascript regular expressions

//Alphanumeric validations
function validatealphanumeric(name)
{ 
var letters = /^[0-9a-zA-Z\s]+$/;


if(name.match(letters))
{
return true;
}
else
{

return false;
}
}


Usage:

var empnumber=trim(document.getElementById('name').value);

if(validatealphanumeric(empnumber))
    {
    //return true
    }
    else if((empnumber=="") || (empnumber=="0") || (empnumber=="null")  || (empnumber=="NIL") || (empnumber=="nil"))
    {
       alert('Please enter valid Employee Number'); 
       return false;
    }
    else
    {
       alert('Employee Number must have alphanumeric characters only');
       return false;
    }