/* ---EMAIL VALIDATION-------------------------------------------------------- */
function is_valid_email(email){
    return /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/.test(email);
}

function validate_membership(form){
    var valid = true;
    for(var i=0;i<(form.length-1);i++){
        if(form[i].value==''){
            alert('All fields are required');
            valid=false;
            break;
        }
        if(form[i].name=='email'){
            if(!is_valid_email(form[i].value)){
                alert('Email field must be valid');
                valid=false;
                break;
            }
        }
    }
    return valid;
}