@solana/sysvars

@solana/sysvars

This packages contains types and helpers for fetching and decoding Solana sysvars. It can be used standalone, but it is also exported as part of the Solana JavaScript SDK @solana/web3.js@experimental.

More information about the available sysvars on Solana can be found in the docs at https://docs.solanalabs.com/runtime/sysvars.

All currently available sysvars can be retrieved and/or decoded using this library.

Sysvar API

This package offers a simple API for working with sysvars.

One can fetch an encoded sysvar account using an RPC client.

const maybeEncodedClock = await fetchEncodedSysvarAccount(rpc, SYSVAR_CLOCK_ADDRESS);
maybeEncodedClock satisfies MaybeEncodedAccount<'SysvarC1ock11111111111111111111111111111111'>;

One can also attempt to fetch a JSON-parsed sysvar account.

const maybeJsonParsedClock = await fetchJsonParsedSysvarAccount(rpc, SYSVAR_CLOCK_ADDRESS);
maybeJsonParsedClock satisfies
    | MaybeAccount<JsonParsedSysvarAccount, 'SysvarC1ock11111111111111111111111111111111'>
    | MaybeEncodedAccount<'SysvarC1ock11111111111111111111111111111111'>;

Each sysvar within the library ships with its own codec for deserializing the account data.

You can pair this codec with the helpers from @solana/accounts to assert and decode sysvar account data.

// Fetch.
const clock = await fetchEncodedSysvarAccount(rpc, SYSVAR_CLOCK_ADDRESS);
clock satisfies MaybeEncodedAccount<'SysvarC1ock11111111111111111111111111111111'>;

// Assert.
assertAccountExists(clock);
clock satisfies EncodedAccount<'SysvarC1ock11111111111111111111111111111111'>;

// Decode.
const decodedClock = decodeAccount(clock, getSysvarClockDecoder());
decodedClock satisfies Account<SysvarClock, 'SysvarC1ock11111111111111111111111111111111'>;

Each supported sysvar also ships with its own fetch-and-decode function to perform the steps above and return the decoded sysvar data.

const clock: SysvarClock = await fetchSysvarClock(rpc);

Supported Sysvars:

This package supports the following Solana sysvars:

• Clock
• EpochRewards
• EpochSchedule
• Fees
• LastRestartSlot
• RecentBlockhashes
• Rent
• SlotHashes
• SlotHistory
• StakeHistory

The Instructions sysvar is also supported but does not exist on-chain, therefore has no corresponding module or codec.