@polkadot/api-contract packages is to be used alongside the
@polkadot/api package. With that in-mind we can install from npm, so we are not going to waste too much time with the bare basics, just install the API & contracts extensions via
yarn add @polkadot/api @polkadot/api-contract
Generally you would want to keep the versions of the 2 in lock-step, which mean that if you upgrade one or the other, ensure that the versions continue to match.
Be aware that Substrate chains are different, which means that some chains will not have the Substrate contracts palette installed. For instance relay chains such as Polkadot does not have this functionality, however may have parachains that do.
Additionally the contracts palette and ink! are still evolving. With the upgrade from ink! v2 to v3 the ABI structure has changed completely. As of the polkadot-js API v2.2.1 only ink! v3.0-rc1 and later is supported. If you are using an earlier version, this guide will not be useful since the wrapper interfaces have changed in a major may to support the new formats.
For development purposes it generally is preferred to use a local development network, that way you can swap and purge contracts while developing.
So we have it installed, you have a development chain running (see the ink! examples for that) and we can jump into actual real-world usage. But before we do, let's take a brief tour through the base classes and interfaces before we get into using them.