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PolkadotJS

Polkadot-JS is a collection of tools that interfaces with the Polkadot blockchain in a granular way.

Primary Implementation

Polkadot-JS as a term has multiple moving parts that are worth mentioning.

Polkadot-JS UI

The Polkadot-JS UI is a hosted application that loads in your browser. The UI has a standard DNS hosted version, which always has the latest features, and an IPFS version that is less frequently updated but is more decentralized. This is also often referred to as Polkadot-JS Apps, or the Apps UI.

Polkadot-JS Apps has many capabilities that go beyond basic wallet functions such as account creation and sending or receiving transactions.

Polkadot-JS Extension

The extension is a simple tool for managing accounts in a browser extension and allowing the signing of extrinsics using these accounts. The Polkadot-JS extension is not made for users to interact with on-chain functions as one would find through a wallet app. The extension acts as a robust key-store and thus acts as an account manager for Substrate-based accounts.

However, it also provides a simple interface for interacting with extension-compliant dApps.

Polkadot-JS Phishing List

The phishing list website is a community-driven curation of less-than-honest operators. The Polkadot-JS extension uses this list to warn a user about suspicious URLs and addresses that are part of the list, and automatically blocks the account address.

Polkadot-JS API

A JavaScript API allowing for programs to interface with the functionality of Polkadot.

Polkadot-JS Apps

Polkadot-JS Apps is the native Polkadot/Kusama/Substrate UI for interacting with a node, allowing access to all features available on Substrate chains. Polkadot-JS Apps also allows developers to to interface with a local node.

Note that the UI may not precisely align with the functionality of individual parachains.

Among other things, Polkadot-JS Apps allows a user to:

Developers

A developer can utilize Polkadot-JS Apps to test your code's functionality. Interacting with the Polkadot-JS comes down to either querying on-chain data or issuing an extrinsic.

Querying on-chain data

To populate the Apps UI, the web app queries the Polkadot-JS API. The API then queries a Polkadot node and uses JavaScript to return information that the UI will display on the screen. You can choose which node to connect to by changing it in the upper-left-hand corner of the screen.

Issuing an extrinsic

Extrinsics are pieces of information that come from outside the chain and are included in a block. Extrinsics can be one of three types: inherents, signed, and unsigned transactions.

Most extrinsics displayed on Polkadot-JS Apps are signed transactions. Inherits are non-signed and non-gossiped pieces of information included in blocks by the block author, such as timestamps, which are “true” because a sufficient number of validators have agreed about validity.

Unsigned transactions are information that does not require a signature but will require some sort of spam prevention, whereas signed transactions are issued by the originator account of a transaction which contains a signature of that account, which will be subject to a fee to include it on the chain.

Considerations

For more user-friendly wallets, check out the supported and treasury-funded wallets on the Wallets Page

Resources

Beginner's Guide to Polkadot-JS

Documentation