NULS SDK has been designed as a modular multi package javascript library that allows you to handle every day blockchain related tasks, like managing an account, make transfers, stake nuls in some consensus node, or interact with some smart contract building an awesome decentralized application.
All the packages are distributed under the @nuls.io namespace. You should install NULS SDK packages as local dependencies in your project:
# In your existing project root folder
$ npm i @nuls.io/core @nuls.io/account @nuls.io/transaction