How to get the validators detail information

Question

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,

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");
console.log(exposures.others.length)

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.