diff --git a/static/js/dict.js b/static/js/dict.js
new file mode 100644
index 0000000000..7d9f844991
--- /dev/null
+++ b/static/js/dict.js
@@ -0,0 +1,77 @@
+/* Constructs a new Dict object.
+ *
+ * Dict() -> the new Dict will be empty
+ * Dict(otherdict) -> create a shallow copy of otherdict
+ * Dict(jsobj) -> create a Dict with keys corresponding to the properties of
+ *                jsobj and values corresponding to the value of the appropriate
+ *                property
+ */
+function Dict(obj) {
+    var self = this;
+    this._items = {};
+
+    if (typeof obj === "object" && obj !== null) {
+        if (obj instanceof Dict) {
+            _.each(obj.items(), function (kv) {
+                self.set(kv[0], kv[1]);
+            });
+        } else {
+            _.each(obj, function (val, key) {
+                self.set(key, val);
+            });
+        }
+    }
+}
+
+(function () {
+
+function munge(k) {
+    return ':' + k;
+}
+
+function unmunge(k) {
+    return k.substr(1);
+}
+
+Dict.prototype = {
+    get: function Dict_get(key) {
+        return this._items[munge(key)];
+    },
+
+    set: function Dict_set(key, value) {
+        return (this._items[munge(key)] = value);
+    },
+
+    has: function Dict_has(key) {
+        return _.has(this._items, munge(key));
+    },
+
+    del: function Dict_del(key) {
+        return delete this._items[munge(key)];
+    },
+
+    keys: function Dict_keys() {
+        return _.map(_.keys(this._items), unmunge);
+    },
+
+    values: function Dict_values() {
+        return _.values(this._items);
+    },
+
+    items: function Dict_items() {
+        return _.map(_.pairs(this._items), function (pair) {
+            return [unmunge(pair[0]), pair[1]];
+        });
+    }
+};
+
+Dict.prototype = _.object(_.map(Dict.prototype,
+                                function (value, key) {
+                                    return [key, util.enforce_arity(value)];
+                                }));
+
+}());
+
+if (typeof module !== 'undefined') {
+    module.exports = Dict;
+}
diff --git a/tools/jslint/check-all.js b/tools/jslint/check-all.js
index f320982b87..92bc13a240 100644
--- a/tools/jslint/check-all.js
+++ b/tools/jslint/check-all.js
@@ -25,7 +25,7 @@ var globals =
     + ' composebox_typeahead typeahead_helper notifications hashchange'
     + ' invite ui util activity timerender MessageList blueslip unread stream_list'
     + ' onboarding message_edit tab_bar emoji popovers navigate message_tour'
-    + ' avatar feature_flags search_suggestion referral stream_color'
+    + ' avatar feature_flags search_suggestion referral stream_color Dict'
 
     // colorspace.js
     + ' colorspace'
diff --git a/zerver/tests/frontend/node/dict.js b/zerver/tests/frontend/node/dict.js
new file mode 100644
index 0000000000..a96d7ef14f
--- /dev/null
+++ b/zerver/tests/frontend/node/dict.js
@@ -0,0 +1,66 @@
+global._ = require('third/underscore/underscore.js');
+global.util = require('js/util.js');
+var Dict = require('js/dict.js');
+var assert = require('assert');
+
+(function test_basic() {
+    var d = new Dict();
+
+    assert.deepEqual(d.keys(), []);
+
+    d.set('foo', 'bar');
+    assert.equal(d.get('foo'), 'bar');
+
+    d.set('foo', 'baz');
+    assert.equal(d.get('foo'), 'baz');
+
+    d.set('bar', 'qux');
+    assert.equal(d.get('foo'), 'baz');
+    assert.equal(d.get('bar'), 'qux');
+
+    assert.equal(d.has('bar'), true);
+    assert.equal(d.has('baz'), false);
+
+    assert.deepEqual(d.keys(), ['foo', 'bar']);
+    assert.deepEqual(d.values(), ['baz', 'qux']);
+    assert.deepEqual(d.items(), [['foo', 'baz'], ['bar', 'qux']]);
+
+    d.del('bar');
+    assert.equal(d.has('bar'), false);
+    assert.strictEqual(d.get('bar'), undefined);
+
+    assert.deepEqual(d.keys(), ['foo']);
+}());
+
+(function test_restricted_keys() {
+    var d = new Dict();
+
+    assert.equal(d.has('__proto__'), false);
+    assert.equal(d.has('hasOwnProperty'), false);
+    assert.equal(d.has('toString'), false);
+
+    assert.strictEqual(d.get('__proto__'), undefined);
+    assert.strictEqual(d.get('hasOwnProperty'), undefined);
+    assert.strictEqual(d.get('toString'), undefined);
+
+    d.set('hasOwnProperty', function () {return true;});
+    assert.equal(d.has('blah'), false);
+
+    d.set('__proto__', 'foo');
+    d.set('foo', 'bar');
+    assert.equal(d.get('foo'), 'bar');
+}());
+
+(function test_construction() {
+    var d1 = new Dict();
+
+    assert.deepEqual(d1.items(), []);
+
+    var d2 = new Dict({foo: 'bar', baz: 'qux'});
+    assert.deepEqual(d2.items(), [['foo', 'bar'], ['baz', 'qux']]);
+
+    var d3 = new Dict(d2);
+    d3.del('foo');
+    assert.deepEqual(d2.items(), [['foo', 'bar'], ['baz', 'qux']]);
+    assert.deepEqual(d3.items(), [['baz', 'qux']]);
+}());
diff --git a/zproject/settings.py b/zproject/settings.py
index 8399310b4f..ae22fa0e54 100644
--- a/zproject/settings.py
+++ b/zproject/settings.py
@@ -363,6 +363,7 @@ JS_SPECS = {
 
             'js/feature_flags.js',
             'js/util.js',
+            'js/dict.js',
             'js/setup.js',
             'js/viewport.js',
             'js/rows.js',