JavaScript Hash union.

unionHash.js

var arrayOfProperties = [
    'admin',
    'user',
    'anon'
];

var hash = {
    admin: "Admin",
    user: "user",
    superadmin: 'SuperAdmin'
}

var i;
var key;
var unionHash = {};

for (i = 0; i < arrayOfProperties.length; i++) {
    key = arrayOfProperties[i];

    if (key in hash) {
        unionHash[key] = hash[key];
    }
}

return unionHash