As a developer,I want to use the interface to search this information: which can get the validator detail information like the count of nominators and the commission and others information,

1 Answer 1


Everything that can be read onchain is listed here.

For example, to read the commission:

console.log((await api.query.staking.validators("11uMPbeaEDJhUxzU4ZfWW9VQEsryP9XqFcNRfPdYda6aFWJ")).commission)

Which is a Perbill, fixed point parts per billion, and 11uMPbeaEDJhUxzU4ZfWW9VQEsryP9XqFcNRfPdYda6aFWJ is a totally arbitrary validator of Polkadot today.

You can directly paste this into https://polkadot.js.org/apps/#/js.

To get the count of active nominator who end up backing a validator in era:

const lastEra = (await api.query.staking.currentEra()).unwrap();
const exposures = await api.query.staking.erasStakers(lastEra, "11uMPbeaEDJhUxzU4ZfWW9VQEsryP9XqFcNRfPdYda6aFWJ");

To get the list of all the nominators who casted a vote for 11uMPbeaEDJhUxzU4ZfWW9VQEsryP9XqFcNRfPdYda6aFWJ, you have to iterate the nominators map, but I will leave that up to you to figure out.

  • why i search the exposures.others.length not same as the expore show ? exposures.others.length=302 but the the expore show 342
    – Rose
    Commented Oct 3, 2022 at 13:53
  • should i use currentEra or activeEra?
    – Rose
    Commented Oct 3, 2022 at 15:14
  • I think it is best if you ask the difference between currentEra and activeEra in a new question and we will answer it there.
    – kianenigma
    Commented Oct 4, 2022 at 7:09

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