<!--
/**
Function checkEmail()
Check email address is valid
emailIn - id of input to check str
fieldId - field id used for error message, use 'null' if not required str
*/
function checkEmail(emailIn, fieldId) {
    var email = document.getElementById(emailIn);
    var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
    if (!filter.test(email.value)) {
        if(fieldId == 'null'){
            //alert('You must enter a valid email address.');
        }
        else{
            alert('You must enter a valid email address in field ' + fieldId + ' to invite this person.');  
        }
        return false;
    }
    else{
        return true;    
    }
}
-->