user-groups: Create static/js/user_groups.js.

static/js/user_groups.js

@@ -0,0 +1,60 @@
+var user_groups = (function () {
+
+var exports = {};
+
+var user_group_name_dict;
+var user_group_by_id_dict;
+
+// We have an init() function so that our automated tests
+// can easily clear data.
+exports.init = function () {
+    user_group_name_dict = new Dict({fold_case: true});
+    user_group_by_id_dict = new Dict();
+};
+
+// WE INITIALIZE DATA STRUCTURES HERE!
+exports.init();
+
+exports.add = function add(user_group) {
+    user_group_name_dict.set(user_group.name, user_group);
+    user_group_by_id_dict.set(user_group.id, user_group);
+};
+
+exports.get_user_group_from_id = function (group_id) {
+    if (!user_group_by_id_dict.has(group_id)) {
+        blueslip.error('Unknown group_id in get_user_group_from_id: ' + group_id);
+        return undefined;
+    }
+    return user_group_by_id_dict.get(group_id);
+};
+
+exports.get_user_group_from_name = function (name) {
+    if (!user_group_name_dict.has(name)) {
+        blueslip.error('Unknown name in get_user_group_from_name: ' + name);
+        return undefined;
+    }
+    return user_group_name_dict.get(name);
+};
+
+exports.get_realm_user_groups = function () {
+    return user_group_name_dict.values();
+};
+
+exports.initialize = function () {
+    _.each(page_params.realm_user_groups, function (user_group) {
+        exports.add(user_group);
+    });
+
+    delete page_params.realm_user_groups; // We are the only consumer of this.
+};
+
+exports.is_user_group = function (item) {
+    return item.hasOwnProperty('members');
+};
+
+return exports;
+
+}());
+if (typeof module !== 'undefined') {
+    module.exports = user_groups;
+}