Overview

These sections should provide you with all the information needed to install the @polkadot/api package, understand the structure of the interfaces and allow you to start using it. For existing users this really should be titled "Things I wish I knew before I started using the api" - it really aims to close the gap to allow anybody to get to grips with using the packages.

We are basing all our examples on the ApiPromise version of the API, however there is also an RxJS version available. Since Promises are a part of the ES2015 specification, it covers the greater amount of use and is the one that will be used in 95% of the cases and should be familiar to 100% of all developers.

For now... just ignore the various flavors and focus on understanding the concepts.

ES2015 Usage and examples

Before we jump into the guide, be aware that in all cases we are using ES2015, including using things like async/await, import and others. Depending on your environment, this may require some adjustments.

While we are using the await naked in all examples (this removes boilerplate and allows us to focus on the actual libraries), and unless your environment supports top-level await, it will need to be wrapped in an async block. So basically to make it run-able we should wrap all samples inside a async function main () { ... } and then just call main().then(() => console.log('completed')).

In the case of Node.js you would change the import into require, i.e.

// Import
const { ApiPromise, WsProvider } = require('@polkadot/api');
...

While Node.js versions >=12 support the import syntax, we are only exporting CommonJS modules, hence the need for require.

What this is not

This is not line-by-line documentation of all the existing function calls available, nor it is tied to a specific chain. (Although the examples do refer to the base Polkadot & Substrate chains). There will be some things in the API that are probably not covered, which brings us to the next point...

Help us help others

If you spot gaps in the information provided, or are uncertain about any specific area, please do log an issue or if you are that way inclined, make a pull-request. We really want to have good documentation in these areas and allow people to be productive right from the start.

Ready? Steady? Go!

If you already have a good grasp on the API and are just looking for a specific answer, you may want to take a look at the Frequently Asked Questions. With all that said, let's get started... What should be installed, and how should we do it?