configcat / common-js

Common Javascript library for ConfigCat. ConfigCat is a hosted feature flag service: https://configcat.com. Manage feature toggles across frontend, backend, mobile, desktop apps. Alternative to LaunchDarkly. Management app + feature flag SDKs.

ConfigCat Common library for JavaScript

ConfigCat Common library for JavaScript is a shared package that provides the common ConfigCat SDK logic for ConfigCat SDK for Node.js and ConfigCat SDK for JavaScript.

ConfigCat is a feature flag, feature toggle, and configuration management service that lets you launch new features and change your software configuration remotely without actually (re)deploying code. ConfigCat even helps you do controlled roll-outs like canary releases and blue-green deployments.

ConfigCat is a hosted feature flag service. Manage feature toggles across frontend, backend, mobile, desktop apps. Alternative to LaunchDarkly. Management app + feature flag SDKs.

Installing

npm install

Running the tests

npm test

Need help?

https://configcat.com/support

Contributing

Contributions are welcome. For more info please read the Contribution Guideline.

About ConfigCat

• Documentation
• Blog

Troubleshooting

Make sure you have the proper Node.js version installed

You might run into errors caused by the wrong version of Node.js. To make sure you are using the recommended Node.js version follow these steps.

1. Have nvm (Node Version Manager - https://github.com/nvm-sh/nvm ) installed:
2. Run nvm install. This will install the compatible version of Node.js.
3. Run nvm use. This will use the compatible version of Node.js.

common-js's Issues

BUG - Update to 1.4.0

Current Behavior

Uncaught TypeError: ConfigServiceBase_1.ProjectConfig is not a constructor

Possible Solution

export ProjectConfig

Detailed Description

common-js/src/ConfigServiceBase.ts

Line 3 in d261a2c

import { ProjectConfig } from "./ProjectConfig";

Passing NaN as pollIntervalSeconds interval causes setTimeout infinity call

Describe the bug

Passing NaN as pollIntervalSeconds interval causes setTimeout infinity call, that in turn millions requests to config-cat CDN

To reproduce

Pass undefined casted to Number as parameter

const myConfig = new Map();
myConfig.set('pollIntervalSeconds', undefined);
new AutoPollOptions("APIKEY", "common", "1.0.0", { pollIntervalSeconds: +(myConfig.get('pollIntervalSeconds')) }, null);

Expected behavior

Configcat client should validate this wrong parameter and throw an exception

Here is recursive with 0 seconds duration
https://github.com/configcat/common-js/blob/master/src/AutoPollConfigService.ts#L91

e.Equals is not a function

My team is occasionally seeing end users run into an e.Equals is not a function exception:

Do you have any idea what may be causing this? Is there a workaround?

Tearing down / stopping polling

How would I cleanly tear down a client instance? For context, I am writing a react hooks integration for our project and I can't find a way to remove the timers that the Autopoller creates. If I were to create an instance of configcat in a component I would be unable to clean it up on unmount, leading to memory leaks.

I'd expect to be able to do something like:

const ConfigCat = ({ children }) => {
  const clientRef = useRef(configcat.createClient());
  useEffect(() => {
    // on unmount stop polling and cleanup
    return () => clientRef.current.cleanup();
  }, [clientRef.current]);
  return (
    <ConfigCatContext.Provider value={clientRef.current}>
      {children}
    </ConfigCatContext.Provider>
  );
}

Unnecessary 'util' dependency breaks Expo compatibility

The following line adds a Node.js dependency that could be easily replaced:

common-js/src/RolloutEvaluator.ts

Line 5 in b587bdf

import { isUndefined } from "util";

Removing this import and defining the following function would make ConfigCat compatible with Expo applications:

function isUndefined(obj: any): boolean {
    return obj === undefined;
}

I've tested ConfigCat with these changes, and the modified version works nicely on Expo.

Please consider making this change. Thank you.

Odd? values in DataGovernance enum

Describe the bug

Hello, I'm currently working on updating the Ember addon we published for ConfigCat.
I ran into some TypeScript error: when trying to build a typed options object for the ConfigCat Client, I noticed some difference between the DataGovernance exported here

common-js/src/ConfigCatClientOptions.ts

Line 8 in df5ef91

export enum DataGovernance {

and the value expected by the documentation here https://configcat.com/docs/sdk-reference/js#auto-polling-default
Which are the correct values?:

• 0 or 1
• Global or EuOnly?

To reproduce

TypeScript Sandbox https://www.typescriptlang.org/play?#code/PQKhAIGEHsDsBcBO0A254AsCm4XQMYCG8AlnONAGbrbj5yUkDmAdAFYDO5jKWHdceIRKwRTcAE9oAV0ThKWYrJyUUhJv0KwAJuA5Z4pWBvAB3EphE0cMWIyaRiUACIA5FuBDAAUFgAeAA7QiPDgWLDSALbgzsSEAOLQAG5YiLBa+DgA3t7geeCgEADKWLz4oZb8JNRSsvKK8MryaiaEiDgB0gBGKCQc2Lrw0OCEKGhMeF2jLq7gsNDafB5eufnxk9MAvOAADAA0q3mF4CVlFRh94NWSMnIKSu3N6pqPnT19A+jDkG5zC3wUWAoCRXWDWcAAUQAqssfPlIdIAPJAkHbACM3gAvt4cSJ4KlKIRMuBEQFSHB+Dl4do4okUmkMlgAFwxWnJVLpWCZADcWJx9FgHFC0DJZEFOxZpPJgvA2yp+RpQjpHMZLIA5OtoFMUGq+fyKcLRRS0ZKjTK5YdwIqEuyGVzmbssUA

Expected behavior

From my point of view, I wonder if the enum values should be Global/EuOnly instead

Screenshots

None

Race condition with `client.dispose()`

Describe the bug

We have a fast running node script which hangs because of the configcat client, even though we call it's dispose function at the end.

Digging into the issue, we see that the dispose method calls clearTimeout(this.timerId), where timerId is undefined. At this time, it's still invoking refreshLogic for the first time. After refreshLogic finishes, it sets a timeout to refresh again, even after the client has been disposed. This causes the process to hang.

To reproduce

Run this script with node:

const configcat = require('configcat-node').createClient('<<SDK KEY>>)
configcat.dispose()

Expected behavior

Node process should exit. Instead it hangs.

Allow optional custom fields

We would like to use some optional custom fields in the configcat user. Actually the typings don't allow optional strings as custom fields and we have to use a workaround.

Please allow undefined as value in the custom object: https://github.com/configcat/common-js/blob/master/src/RolloutEvaluator.ts#L31

custom?: { [key: string]: string | undefined } = {};

Marking bundle side effect free

According to https://bundlephobia.com/[email protected], the bundle is tree-shakable but not marked as side effect free.

After having a quick check on the code, the bundle could be marked as side effect free like so: https://webpack.js.org/guides/tree-shaking/#mark-the-file-as-side-effect-free

Any concerns in doing so?

With autopoll initial tryReadFromCache takes 5 seconds

Describe the bug

We're using a toggle immediately after loading our application and noticed a 5 second delay of our application loading. After debugging the problem I noticed that although the configcat cdn replies within 30ms, the first client.getValueAsync still takes almost 5 seconds (default config value for maxInitWaitTimeSeconds).

Our configuration: configcat-js v5.7.2 with AutoPoll:

import { createClientWithAutoPoll, createConsoleLogger } from 'configcat-js'
const logger = createConsoleLogger(LogLevel.Off)
const client = createClientWithAutoPoll('our-key', {
    logger,
    pollIntervalSeconds: 300,
    requestTimeoutMs: 5000,
  })

const getValue =  <T>(featureName: string, defaultValue: T, context: any) => client.getValueAsync(featureName, defaultValue, context)

Expected behavior

Since loading the config takes about 25ms and evaluation of most settings about 15ms I would expect a responsetime of approx 40ms.

Cause of the issue:

• AutoPollConfigService.tryReadFromCache checks for timeStamp of the cache (line 85) and will keep waiting for a cache update until maxInitWaitTimeStamp has passed;
• AutoPollConfigService.startRefreshWorker calls refreshLogic with forceUpdateCache = false (line 64), therefore ConfigServiceBase.refreshLogicBaseAsync will not update the cache if the configuration hasn't changed since the last visit to our website. Since cache is persisted in localstorage it will still have the old timestamp.

Suggested solution:

Code change in AutoPollConfigService.ts to force cache update on startup:

line 20:

this.startRefreshWorker(autoPollConfig.pollIntervalSeconds * 1000, true);

startRefreshWorker:

    private startRefreshWorker(delay: number, forceUpdateCache = false) {
        this.refreshLogic(forceUpdateCache).then((_) => {
            if (this.disposed) {
                return;
            }
            this.timerId = setTimeout(
                () => {
                    this.startRefreshWorker(delay);
                },
                delay);
        });
    }