The extremum client library for JavaScript and TypeScript can be installed using npm:
$ npm install extremum-sdk
const client = new ExtremumSDK('0', '<your-instance-domain>');
// Get the first 10 features
// and display their names in the console
const { result } = await client.management.function.getFunctions(0, 10);
result.forEach(fun => console.log(fun.name));