client/config

This module reads config data from window.configData (passed from the Node.js server in the HTML response) and initializes a config object that is used to read these values.

You can read more about how to use config in the config documentation.

Feature Flags API

The config files contain a features object that can be used to determine whether to enable a feature for certain environments. This allows us to merge in-progress features without launching them to production.

config.isEnabled( key )

Is a feature enabled?

import config from '@automattic/calypso-config';

if ( config.isEnabled( 'myFeature' ) ) {
    // do something only when myFeature is enabled
}

config.enable( key )

Enable a feature.

import config from '@automattic/calypso-config';

config.enable( 'myFeature' );

config.disable( key )

Disable a feature.

import config from '@automattic/calypso-config';

config.disable( 'myFeature' );

The key should always be a literal string not a variable so that down the road we can process the compiled scripts and remove code for disabled features in production.

When Calypso is running in development mode or in the stage environment, you can specify a ?flags= query argument or a flags cookie to modify feature flags for each full page load.

Query argument examples:

?flags=flag1: Enable feature flag1.
?flags=-flag2: Disable feature flag2.
?flags=+flag1,-flag2: Enable feature flag1 and disable feature flag2.

You can use the same syntax in a cookie or via session storage

Cookies:

document.cookie = 'flags=+flag1,-flag2;max-age=1209600;path=/';: Enable feature flag1 and disable feature flag2.
document.cookie = 'flags= ; expires=Thu, 01 Jan 1970 00:00:00 GMT; path=/;';: Reset flags cookie to config values.

Session Storage:

window.sessionStorage.setItem( 'flags', 'flag1,-flag2' );: Enable feature flag1 and disable feature flag2.
window.sessionStorage.removeItem( 'flags' );: Reset flags session item to config values.

Note: the flags query argument, cookie, and sessionStorage won't work for feature flags used by Node.js server. For this case, you can use the ENABLE_FEATURES and/or DISABLE_FEATURES environment variables instead.

Testing for calypso.live environment

We often need to enable or disable certain features not only based on the Calypso environment (development, production, staging, horizon, ...) but also when Calypso runs in the calypso.live testing environment. The config module exports a helper function isCalypsoLive that returns true if Calypso is running on the *.calypso.live origin.

import { isCalypsoLive } from '@automattic/calypso-config';

if ( isCalypsoLive() ) {
    /* ... */
}