Edgio Experimentation

Overview

The @edgio/experimentation package provides utilities to extract experiment and variant information from both the x-edg-experiments-info origin header and server timing response headers. This allows customers to easily access and utilize the experiment and variant information in their applications.

Installation

To use this package in your project, you can install it via npm or yarn:

npm install @edgio/experimentation

# or

yarn add @edgio/experimentation

Accessing Information in Frontend through Server-Timing Header

Each response with experiments information will have a Server-Timing header that has a value similar to this:

Server-Timing: edgio_cache;desc=TCP_MISS,edgio_pop;desc=dcd,edgio_country;desc=UA,experiments;desc=%7B%22Testing_new_page_1238476236%22%3A%22New_page_816213%22%2C%22New_Banner_Test_8123712%22%3A%22Old_banner_712312%22%7D

The Experimentation information in this header (encoded in the experiments description field) can be access like so:

import { getInfoForPath } from '@edgio/experimentation';

const relativeUrl = '/path/to/resource';
getInfoForPath(relativeUrl).then((info) => {
    if (info) {
        console.log(info);
    } else {
        console.log('No experimentation info found for the given path.');
    }
});

/*
{
    "Testing_new_page_1238476236": "New_page_816213",
    "New_Banner_Test_8123712": "Old_banner_712312"
}
 */

This can be parsed as JSON in your application, giving you a map of Experiment IDs (keys) and their corresponding Variant IDs (values).

You can also use our open-source Experiments library to parse this information as shown below.

Accessing Information in Backend through x-edg-experiments-info Header

For the request in the example above, when it is received in your backend, it will have the following x-edg-experiments-info header:

x-edg-experiments-info: %7B%22Testing_new_page_1238476236%22%3A%22New_page_816213%22%2C%22New_Banner_Test_8123712%22%3A%22Old_banner_712312%22%7D

Similar to the frontend, this header value can be parsed like so:

import { parseInfoFromValue } from '@edgio/experimentation';
const experimentationInfo = parseInfoFromValue(headers.get('x-edg-experiments-info'));

console.log(experimentationInfo);
/*
{
    "Testing_new_page_1238476236": "New_page_816213",
    "New_Banner_Test_8123712": "Old_banner_712312"
}
*/

The experimentationInfo provides a JSON object that can be used in your application, giving you a map of Experiment IDs (keys) and their corresponding Variant IDs (values).

Error Handling

• If the provided header value is not a string or empty, the parseInfoFromValue function will return an empty JSON object.
• If no experimentation info is found for the given path using getInfoForPath, it will resolve with undefined.

Contribution

We welcome contributions from the community! If you encounter any issues or have suggestions for improvements, please feel free to open an issue or submit a pull request on our GitHub repository.

License

This package is open-source and available under the MIT License. Please refer to the LICENSE file for more details.