Project import generated by Copybara.
GitOrigin-RevId: d9e9e3fb4e31372ec1fb43b178994ca78fa8fe70
diff --git a/static_src/shared/experiments.js b/static_src/shared/experiments.js
new file mode 100644
index 0000000..1528a00
--- /dev/null
+++ b/static_src/shared/experiments.js
@@ -0,0 +1,91 @@
+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview Manages the current user's participation in experiments (e.g.
+ * phased rollouts).
+ *
+ * This file is an early prototype serving the needs of go/monorail-slo-v0.
+ *
+ * The more mature design is under discussion:
+ * http://doc/1rtYXq68WSlTNCzVJiSttLWF14CiK5sOlEef2JWAgheg
+ */
+
+/**
+ * An Enum representing known expreriments.
+ *
+ * @typedef {string} Experiment
+ */
+
+/**
+ * @type {Experiment}
+ */
+export const SLO_EXPERIMENT = 'slo';
+
+const EXPERIMENT_QUERY_PARAM = 'e';
+
+const DISABLED_STR = '-';
+
+const _SLO_EXPERIMENT_USER_DISPLAY_NAMES = new Set([
+ 'jessan@google.com',
+]);
+
+/**
+ * Checks whether the current user is in given experiment.
+ *
+ * @param {Experiment} experiment The experiment to check.
+ * @param {UserV0=} user The current user. Although any user can currently
+ * be passed in, we only intend to support checking if the current user is
+ * in the experiment. In the future the user parameter may be removed.
+ * @param {Object} queryParams The current query parameters, parsed by qs.
+ * We support a string like 'e=-exp1,-exp2...' for disabling experiments.
+ *
+ * We allow disabling so that a user in the fishfood group can work around
+ * any bugs or undesired behaviors the experiment may introduce for them.
+ *
+ * As of now, we don't allow enabling experiments by override params.
+ * We may not want access shared beyond the fishfood group (e.g. if it is a
+ * feature we are likely to change dramatically or take away).
+ * @return {boolean} Whether the experiment is enabled for the current user.
+ */
+export const isExperimentEnabled = (experiment, user, queryParams) => {
+ const experimentOverrides = parseExperimentParam(
+ queryParams[EXPERIMENT_QUERY_PARAM]);
+ if (experimentOverrides[experiment] === false) {
+ return false;
+ }
+ switch (experiment) {
+ case SLO_EXPERIMENT:
+ return !!user &&
+ _SLO_EXPERIMENT_USER_DISPLAY_NAMES.has(user.displayName);
+ default:
+ throw Error('Unknown experiment provided');
+ }
+};
+
+/**
+ * Parses a comma separated list of experiments from the query string.
+ * Experiment strings preceded by DISABLED_STR are overrode to be disabled,
+ * otherwise they are to be enabled.
+ *
+ * Does not do any validation of the experiment string provided.
+ *
+ * @param {string?} experimentParam comma separated experiements.
+ * @return {Object} Maps experiment name to whether enabled or
+ * disabled boolean. May include invalid experiment names.
+ */
+const parseExperimentParam = (experimentParam) => {
+ const experimentOverrides = {};
+ if (experimentParam) {
+ for (const experimentOverride of experimentParam.split(',')) {
+ if (experimentOverride.startsWith(DISABLED_STR)) {
+ const experiment = experimentOverride.substr(DISABLED_STR.length);
+ experimentOverrides[experiment] = false;
+ } else {
+ experimentOverrides[experimentOverride] = true;
+ }
+ }
+ }
+ return experimentOverrides;
+};