Functional BitWise Role Checking

roleCheck.js

var roles = {'admin': 8, 'user': 1, 'powerUser': 4 },
    user = {role: 12}; // 4 + 8
function hasRoleName(chkRole) {
    chkRole = typeof(chkRole) === 'string' ? [chkRole] : chkRole;
    var roleSum = chkRole.reduce(function(last, curr, idx, list) { return last + (roles[list[idx]] || 0); }, 0);
    return hasAnyRolesBit(roleSum);
}
function hasAllRolesBit(roleSum) {
    return (roleSum & user.role) >= roleSum;    // must match all bits!
}
function hasAnyRolesBit(roleSum) {
    return (roleSum & user.role) > 0;           // true if *any* flag matches
}

user = {role: 12};
assert(hasRoleName('admin'));
assert(hasRoleName('powerUser'));
assert(!hasRoleName('user'));
// now try this user's role...
user = {role: 5};
assert(!hasRoleName('admin'));
assert(hasRoleName('powerUser'));
assert(hasRoleName('user'));