JavaScript & Node
You can find the Node SDK on npm. Implementation details can be found on the libraries GitHub.
Example
const manager = new FeatureSwitchManager("some-api-key", "stage");
const result = await manager.getSwitchValue("devToolsEnabled");
if(result.value) {
// switch is on
} else {
// switch is off
}
const switches = await manager.getSwitches();
const found = switches.find(fs => fs.key === 'devToolsEnabled');
if(found && found.value) {
// switch is on
}