JavaScript / TypeScript (Client-Side) SDK

Introduction

Welcome to the developer documentation for the Kameleoon JavaScript / TypeScript SDK! Our SDK gives you the possibility of running experiments and activating feature flags on your front-end JavaScript application. Integrating our SDK into your web-application is easy, and its footprint (in terms of memory and network usage) is low.

You can refer to the SDK reference to check out all possible features of the SDK. Also make sure you check out our Getting started tutorial which we have prepared to walk you through the installation and implementation.

Latest version of the JavaScript SDK: 1.0.7 (changelog).

Getting started

This guide is designed to help you integrate our SDK in a few minutes and start running experiments in your JavaScript applications. This tutorial will explain the setup of a simple A/B test to change the number of recommended products based on different variations.

Creating an experiment

First, you must create an experiment in the Kameleoon back-office so that our platform is aware of the new A/B test you're planning to implement on your side. Make sure that server-side type is chosen as shown below:

Upon successful creation of the experiment, you will need to get its ID to use in the SDK as an argument to the triggerExperiment() method.

Installing the SDK

Installing the JavaScript client

npm install kameleoon-client-javascript

Installing the SDK can be directly achieved through an NPM module. Our module is hosted on official npm repositories, so you just have to run the following command:

npm install kameleoon-client-javascript

Additional configuration

You can configure parameters for the JavaScript SDK via a JSON object containing configuration keys (and their associated values). You should pass this configuration object as an argument to the KameleoonClient() constructor method. With the current version of the JavaScript SDK, those are the available keys:

• actions_configuration_refresh_interval: this specifies the refresh interval, in minutes, of the configuration for experiments and feature flags (the active experiments and feature flags are fetched from the Kameleoon servers). It means that once you launch an experiment, pause it, or stop it the changes can take (at most) the duration of this interval to be propagated in production to your servers. If not specified, the default interval is 60 minutes.
• visitor_data_maximum_size: this specifies the maximum amount of memory that the map holding all the visitor data (in particular custom data) can take (in MB on the browser LocalStorage). If not specified, the default size is 1MB.
• environment: an option specifying which feature flag configuration will be used, by default each feature flag is split into production, staging, development. If not specified, will be set to default value of production. More information

Initializing the Kameleoon client

let {KameleoonClient, KameleoonData, KameleoonException} = require("kameleoon-client-javascript");

let siteCode = "a8st4f59bj";

let kameleoonClient = new KameleoonClient(siteCode);

kameleoonClient = new KameleoonClient(siteCode, false, {"actions_configuration_refresh_interval": 5});

// Second version of the KameleoonClient, using an asynchronous triggerExperiment() method
kameleoonClient = new KameleoonClient(siteCode, true);

After installing the SDK into your application and setting up a server-side experiment on Kameleoon's back-office, the next step is to create the Kameleoon client in your application code.

The code on the right gives a clear example. A KameleoonClient is a singleton object that acts as a bridge between your application and the Kameleoon platform. It includes all the methods and properties you will need to run an experiment. The KameleoonClient needs to be initialized with an HTTP call, so all code that will use this object should be wrapped as a function callback, passed to the KameleoonClient.runWhenReady() method. All further examples use this approach.

Triggering an experiment

let visitorCode = kameleoonClient.obtainVisitorCode("example.com");
let recommendedProductsNumber;

kameleoonClient.runWhenReady(function () {
    let variationID;

    try {
        variationID = kameleoonClient.triggerExperiment(visitorCode, 75253);
    }
    catch (e) {
        if (e.type == KameleoonException.NotTargeted.type) {
            // The user did not trigger the experiment, as the associated targeting segment conditions were not fulfilled. He should see the reference variation
            variationID = 0;
        }
        if (e.type == KameleoonException.NotActivated.type) {
            // The user triggered the experiment, but did not activate it. Usually, this happens because the user has been associated with excluded traffic
            variationID = 0;
        }
        if (e.type == KameleoonException.ExperimentConfigurationNotFound.type) {
            // The user will not be counted into the experiment, but should see the reference variation
            variationID = 0;
        }
    }

    if (variationID == 0) {
        //This is the default / reference number of products to display
        recommendedProductsNumber = 5;
    }
    else if (variationID == 148382) {
        //We are changing number of recommended products for this variation to 10
        recommendedProductsNumber = 10;
    }
    else if (variationID == 187791) {
        //We are changing number of recommended products for this variation to 8
        recommendedProductsNumber = 8;
    }

    // Here you should have code to generate the HTML page back to the client, where recommendedProductsNumber will be used
}, function () {
    console.log("Timeout occured in the JavaScript SDK initialization.");
}, 2000);

Running an A/B experiment on your JavaScript application means bucketing your visitors into several groups (one per variation). The SDK takes care of this bucketing (and the associated reporting) automatically.

Triggering an experiment by calling the triggerExperiment() method will register a random variation for a given visitorCode. If this visitorCode is already associated with a variation (most likely a returning visitor that has already been exposed to the experiment previously), then it will return the previous variation assigned for the given experiment.

Implementing variation code

let recommendedProductsNumber;

if (variationID == 0) {
//This is the default / reference number of products to display
recommendedProductsNumber = 5;
}
else if (variationID.equals == 148382) {
//We are changing number of recommended products for this variation to 10
recommendedProductsNumber = 10;
}
else if (variationID == 187791) {
//We are changing number of recommended products for this variation to 8
recommendedProductsNumber = 8;
}

To execute different code paths depending on the variation assigned to the visitor, you will need the list of all the experiment's variation IDs. You can find these variation IDs (as well as the experiment ID) by opening the experiment in the back-office interface. By convention, the reference (original variation) always has an ID equal to 0.

Once you have the IDs of the different variations, you can implement a different action for each variation, and one of the code paths will be executed, based on the associated variationID for the current visitor. Generally, this can be done using a simple if / else or switch mechanism. In our example, we just change the number of recommended products with two different variations.

Tracking conversion

let visitorCode = kameleoonClient.obtainVisitorCode("example.com");
let goalID = 83023;

kameleoonClient.trackConversion(visitorCode, goalID);

After you are done triggering an experiment, the next step is usually to start tracking conversions. This is done to measure performance characteristics according to the goals that make sense for your business.

For this purpose, use the trackConversion() method of the SDK as shown in the example. You need to pass the visitorCode and goalID parameters so we can correctly track conversions for this particular visitor.

Obtaining results

Once your implementation is in place on the server side (experiment triggering, variations handling, and conversion tracking), it is time to launch the experiment on the Kameleoon platform. You do this in the same way as for a front-end test. Basic operations such as starting, pausing and stopping the experiment work exactly the same way.

After the experiment is launched, the first results will be available on our standard results page in the back-office after a duration of 30 minutes. This is because (as is the case with front-end testing) visits are considered over after 30 minutes of inactivity. Inactivity in this context means the absence of calls sent to the Kameleoon back-end servers (such calls are made via triggerExperiment(), trackConversion() or flush() methods).

Technical considerations

Kameleoon made an important architectural design decision with its SDK technology, namely that every SDK must comply with a zero latency policy. In practice, this means that any blocking remote server call should be banned, as even the fastest remote call would add a 20ms latency to your application. And if for any reason our servers are slower to reply than usual (unfortunately, this can happen), this delay can quickly increase to hundreds of milliseconds, seconds... or even completely block the run of your web-application for the end user. We believe that web performance is of paramount importance in today's world and we don't think adding A/B testing or feature flagging capabilities should come at the cost of a slow down in your web-application.

However, in the case of the JavaScript SDK, since it runs on users' devices, the configuration of all active experiments / feature flags has to be fetched at the start of the session. It cannot be fetched once for every , similarly to the server-side case. This introduces a mandatory distant server call with an associated callback, which means code using the JS SDK (implementing experiments or feature flags) cannot be ran prior to the execution of this callback. For maximal performance, this can be avoided by using our Activation API in tandem with a standard Kameleoon install, where the configuration data is directly embedded in the Kameleoon application file (ie, the JavaScript file contains both the engine code and the configuration of active experiments). But this is a completely different process (advantages of each method are highlighted here), with a different API and no npm package (installation is done by integrating a standard JS tag on the HTML source page). It is described on this article.

Apart from this initial remote call, we guarantee that the use of our SDKs has absolutely no performance impact. Variation allocation for experiments takes place directly on the SDK code (without any distant API call), and tracking calls are made asynchronously in a non-blocking way (in the background).

Having a zero latency policy also imposes some other constraints. The main one is that user data about your visitor should be kept locally, and not fetched from a remote server. For instance, if you set a custom data for a given visitor, we must store this somehow in the user's device. In the case of the JavaScript SDK, this is implemented via a map of visitor data directly on the browser LocalStorage. So if you use new KameleoonData.CustomData() and then kameleoonClient.addData() methods, the information will be stored in the browser's LocalStorage. It should usually not grow too big in size, unless you use an extremely large amount of custom data.

Reference

This is a full reference documentation of the JavaScript SDK.

If this is your first time working with the JavaScript SDK, we strongly recommend you go over our Getting started tutorial to integrate the SDK and start experimenting in a few minutes.

KameleoonClient

KameleoonClient

let kameleoonClient = new KameleoonClient("a8st4f59bj");

kameleoonClient = new KameleoonClient("a8st4f59bj", false, {"actions_configuration_refresh_interval": 5});

The starting point for using the SDK is the initialization step. All interactions with the SDK are done through an object named KameleoonClient, therefore you need to create this object.

Arguments

obtainVisitorCode

const { v4: uuidv4 } = require("uuid");

let visitorCode = kameleoonClient.obtainVisitorCode("example.com");

visitorCode = kameleoonClient.obtainVisitorCode("example.com", visitorCode);

visitorCode = kameleoonClient.obtainVisitorCode("example.com", uuidv4());

The obtainVisitorCode() helper method should be called to obtain the Kameleoon visitorCode for the current visitor. This is especially important when using Kameleoon in a mixed front-end and back-end environment, where user identification consistency must be guaranteed. The implementation logic is described here:

1. First we check if a kameleoonVisitorCode cookie can be found. If so, we will use this as the visitor identifier.

2. If no cookie is found, we either randomly generate a new identifier, or use the defaultVisitorCode argument as identifier if it is passed. This allows our customers to use their own identifiers as visitor codes, should they wish to. This can have the added benefit of matching Kameleoon visitors with their own users without any additional look-ups in a matching table.

3. In any case, the JavaScript kameleoonVisitorCode cookie is set with the value. Then this identifier value is finally returned by the method.

For more information, refer to this article.

Arguments

Return value

triggerExperiment

let visitorCode = kameleoonClient.obtainVisitorCode("example.com");
let experimentID = 75253;
let variationID;

kameleoonClient.runWhenReady(function () {
let variationID;

    try {
        variationID = kameleoonClient.triggerExperiment(visitorCode, experimentID);
    }
    catch (e) {
        if (e.type == KameleoonException.NotTargeted.type) {
            // The user did not trigger the experiment, as the associated targeting segment conditions were not fulfilled. He should see the reference variation
            variationID = 0;
        }
        if (e.type == KameleoonException.NotActivated.type) {
            // The user triggered the experiment, but did not activate it. Usually, this happens because the user has been associated with excluded traffic
            variationID = 0;
        }
        if (e.type == KameleoonException.ExperimentConfigurationNotFound.type) {
            // The user will not be counted into the experiment, but should see the reference variation
            variationID = 0;
        }
    }

}, function () {
console.log("Timeout occured in the JavaScript SDK initialization.");
}, 2000);

To trigger an experiment, call the triggerExperiment() method of our SDK.

This method takes visitorCode and experimentID as mandatory arguments to register a variation for a given user.

If such a user has never been associated with any variation, the SDK returns a randomly selected variation. If a user with a given visitorCode is already registered with a variation, it will detect the previously registered variation and return the variationID.

You have to make sure that proper error handling is set up in your code as shown in the example to the right to catch potential exceptions.

Arguments

Return value

Exceptions Thrown

activateFeature

let visitorCode = kameleoonClient.obtainVisitorCode("example.com");
let featureKey = "new_checkout";
let hasNewCheckout = false;

try {
    hasNewCheckout = kameleoonClient.activateFeature(visitorCode, featureKey);
}
catch (e) {
    if (e.type == KameleoonException.NotActivated.type) {
        // The user did not trigger the feature, as the associated targeting segment conditions were not fulfilled. The feature should be considered inactive
        hasNewCheckout = false;
    }
    if (e.type == KameleoonException.FeatureConfigurationNotFound.type) {
        // The user will not be counted into the experiment, but should see the reference variation
        hasNewCheckout = false;
    }
}

if (hasNewCheckout)
{
    // Implement new checkout code here
}

To activate a feature toggle, call the activateFeature() method of our SDK.

This method takes a visitorCode and featureKey (or featureID) as mandatory arguments to check if the specified feature will be active for a given user.

If such a user has never been associated with this feature flag, the SDK returns a boolean value randomly (true if the user should have this feature or false if not). If a user with a given visitorCode is already registered with this feature flag, it will detect the previous featureFlag value.

You have to make sure that proper error handling is set up in your code as shown in the example to the right to catch potential exceptions.

Arguments

Return value

Exceptions Thrown

obtainVariationAssociatedData

let visitorCode = kameleoonClient.obtainVisitorCode("example.com");
int experimentID = 75253;

try {
let variationID = kameleoonClient.triggerExperiment(visitorCode, experimentID);
let jsonObject = kameleoonClient.obtainVariationAssociatedData(variationID);
let firstName = jsonObject["firstName"];
}
catch (e) {
if (e.type == KameleoonException.VariationConfigurationNotFound.type) {
// The variation is not yet activated on Kameleoon's side, ie the associated experiment is not online
}
}

To retrieve JSON data associated with a variation, call the obtainVariationAssociatedData() method of our SDK. The JSON data usually represents some metadata of the variation, and can be configured on our web application interface or via our Automation API.

This method takes the variationID as a parameter and will return the data as a JavaScript object. It will throw an exception (KameleoonException.VariationConfigurationNotFound) if the variation ID is wrong or corresponds to an experiment that is not yet online.

Arguments

Return value

Exceptions Thrown

obtainFeatureVariable

let featureKey = "myFeature";
let variableKey = "myVariable";
let data;

try {
    data = kameleoonClient.obtainFeatureVariable(featureKey, variableKey);
}
catch (e) {
    if (e.type == KameleoonException.FeatureConfigurationNotFound.type) {
        // The feature is not yet activated on Kameleoon's side
    }
}

To retrieve a feature variable, call the obtainFeatureVariable() method of our SDK. A feature variable can be changed easily via our web application.

This method takes two input parameters: featureKey and variableKey. It will return the data with the expected type, as defined on the web interface. It will throw an exception (KameleoonException.FeatureConfigurationNotFound) if the requested feature has not been found in the internal configuration of the SDK.

Arguments

Return value

Exceptions Thrown

trackConversion

let {KameleoonClient, KameleoonData, KameleoonException} = require("kameleoon-client-javascript");

let visitorCode = kameleoonClient.obtainVisitorCode("example.com");
let goalID = 83023;

kameleoonClient.addData(visitorCode, new KameleoonData.Browser(KameleoonData.browsers.CHROME));
kameleoonClient.addData(
visitorCode,
new KameleoonData.PageView("https://url.com", "title", 3),
new KameleoonData.Interest(2)
);
kameleoonClient.addData(visitorCode, new KameleoonData.Conversion(32, 10, false));

kameleoonClient.trackConversion(visitorCode, goalID);

To track conversion, use the trackConversion() method. This method requires visitorCode and goalID to track conversion on this particular goal. In addition, this method also accepts revenue as a third optional argument to track revenue. The visitorCode is usually identical to the one that was used when triggering the experiment.

The trackConversion() method doesn't return any value. This method is non-blocking as the server call is made asynchronously.

Arguments

addData

let {KameleoonClient, KameleoonData, KameleoonException} = require("kameleoon-client-javascript");
let visitorCode = kameleoonClient.obtainVisitorCode("example.com");

kameleoonClient.addData(visitorCode, new KameleoonData.Browser(KameleoonData.browsers.CHROME));
kameleoonClient.addData(
    visitorCode,
    new KameleoonData.PageView("https://url.com", "title", 3),
    new KameleoonData.Interest(0)
);

kameleoonClient.addData(visitorCode, new KameleoonData.Conversion(32, 10, false));

To associate various data with the current user, we can use the addData() method. This method requires the visitorCode as a first parameter, and then accepts several additional parameters. These additional parameters represent the various Data Types allowed in Kameleoon.

Note that the addData() method doesn't return any value and doesn't interact with the Kameleoon back-end servers by itself. Instead, all declared data is saved for further sending via the flush() method described in the next paragraph. This reduces the number of server calls made, as data is usually grouped into a single server call triggered by the execution of flush().

Arguments

flush

let {KameleoonClient, KameleoonData, KameleoonException} = require("kameleoon-client-javascript");
let visitorCode = kameleoonClient.obtainVisitorCode("example.com");

kameleoonClient.addData(visitorCode, new KameleoonData.Browser(KameleoonData.browsers.CHROME));
kameleoonClient.addData(
visitorCode,
new KameleoonData.PageView("https://url.com", "title", 3),
new KameleoonData.Interest(0)
);

kameleoonClient.addData(visitorCode, new KameleoonData.Conversion(32, 10, false));
kameleoonClient.flush(visitorCode);

Data associated with the current user via addData() method is not immediately sent to the server. It is stored and accumulated until it is sent automatically by the triggerExperiment() or trackConversion() methods, or manually by the flush() method. This allows the developer to control exactly when the data is flushed to our servers. For instance, if you call the addData() method a dozen times, it would be a waste of ressources to send data to the server after each addData() invocation. Just call flush() once at the end.

The flush() method doesn't return any value. This method is non-blocking as the server call is made asynchronously.

Arguments

KameleoonData

Browser

kameleoonClient.addData(visitorCode, new KameleoonData.Browser(KameleoonData.browsers.CHROME));

PageView

kameleoonClient.addData(visitorCode, new KameleoonData.PageView('https://url.com', 'title', 3));

Conversion

kameleoonClient.addData(visitorCode, new KameleoonData.Conversion(32, 10, false));

CustomData

kameleoonClient.addData(visitorCode, new KameleoonData.CustomData(1, 'some custom value'));

Interest

kameleoonClient.addData(visitorCode, new KameleoonData.Interest(0));