This quiz covers the following parts of the Substrate Knowledge Map:
- Polkadot-JS Apps provides a front-end UI and wallet to interact with Substrate-based networks.
- Polkadot-JS API is the official JS API that connects to Substrate-based networks.
- Polkadot-JS API is the official front-end UI to interact with any Substrate-based chain.
- Polkadot-JS API, in addition to Substrate-based networks, can also connect to other mainstream blockchains such as Bitcoin and Ethereum.
2. In Polkadot-JS API, what datatype is used to represent a number (i.e. u64, i64, u128, i128) on a Substrate network?
- The default data type Number in javascript.
- String
- bn.js
- bignumber.js
- decimal.js
3. What is the correct way to query a storage value in a Substrate network and subscribe to its changes?
-
const val = await api.query.my_pallet.storage -
const unsub = await api.query.my_pallet.storage(value => {...}) -
const val = await api.consts.my_pallet.const -
const val = await api.tx.my_pallet.tx().signAndSend() -
const val = await api.tx.my_pallet.tx().signAndSend(value => {...})
4. Assuming that you don't need to subscribe to the on-chain transaction status, what is the proper way to send an extrinsic to a Substrate network?
-
const val = await api.query.my_pallet.storage -
const unsub = await api.query.my_pallet.storage(value => {...}) -
const val = await api.consts.my_pallet.const -
const val = await api.tx.my_pallet.tx().signAndSend() -
const val = await api.tx.my_pallet.tx().signAndSend(value => {...})