Extract 'randao' Value from the Ethereum Beacon Chain Using the Block Details Method
This script extracts the ‘randao’ information from the Beacon chain block details in JavaScript using the Axios package.
const axios = require('axios');
// Declare the beacon provider URL and request parameters.
const BEACON_PROVIDER_URL = "CHAINSTACK_BEACON_URL";
const HEADER = { 'Content-Type': 'application/json' };
const BLOCK_ID = "head";
// Send the request
axios.get(`${BEACON_PROVIDER_URL}/eth/v2/beacon/blocks/${BLOCK_ID}`, { headers: HEADER })
.then(response => {
// Parse the response and log the result.
try {
const parsedJson = response.data;
const slot = parsedJson.data.message.slot;
const randao = parsedJson.data.message.body.randao_reveal;
console.log(`randao value for slot ${slot} is: ${randao}`);
} catch (error) {
console.error(`An error occurred while parsing the response: ${error}`);
}
})
.catch(error => {
console.error(`An error occurred while fetching the data: ${error}`);
});
$ node index
randao value for slot 5717752 is:
0x91bed944631c3178c3c3d2ba2b981b12fc68bfc22e66c7f77477416f9f46837b15ae6cd6feb4347484c83e83751c7cab0bf93e39698eb61ab38fff51727a03a04ee1fa427162fc9539e647619be88b8bb0db37f7d241883371dca99fa049a2be
You will need a Chainstack account and an Ethereum node to follow this recipe.
Install node.js in case it is not installed yet.
Create a new directory for your project.
Initialize an npm project:
npm init
Install the axios package:
npm install axios
Create a new file index.js, import the axios library, and initialize the parameters required for this request.
This script will send a GET request to the Ethereum Beacon chain.
Paste your Beacon Chainstack node URL in the BEACON_PROVIDER_URL const.
Also, set up the request parameters. The BLOCK_ID constant identifies which block to query.
const axios = require('axios');
// Declare the beacon provider URL and request parameters.
const BEACON_PROVIDER_URL = "CHAINSTACK_BEACON_URL";
const HEADER = { 'Content-Type': 'application/json' };
const BLOCK_ID = "head";
The body of the script is the code to send the request.
This part sends a request to the Beacon provider, parses the response, and prints a statement in the console.
// Send the request
axios.get(`${BEACON_PROVIDER_URL}/eth/v2/beacon/blocks/${BLOCK_ID}`, { headers: HEADER })
.then(response => {
// Parse the response and log the result.
try {
const parsedJson = response.data;
const slot = parsedJson.data.message.slot;
const randao = parsedJson.data.message.body.randao_reveal;
console.log(`randao value for slot ${slot} is: ${randao}`);
} catch (error) {
console.error(`An error occurred while parsing the response: ${error}`);
}
})
.catch(error => {
console.error(`An error occurred while fetching the data: ${error}`);
});
This script isolates the slot, and randao fields of the object returned.
They are held in the respective constants and you can wrap this code in a function to return those values and do more processing.
const slot = parsedJson.data.message.slot;
const randao = parsedJson.data.message.body.randao_reveal;
Now you only need to save the file and run it with:
node index
This command will run the program and display the response.
const axios = require('axios');
// Declare the beacon provider URL and request parameters.
const BEACON_PROVIDER_URL = "CHAINSTACK_BEACON_URL";
const HEADER = { 'Content-Type': 'application/json' };
const BLOCK_ID = "head";
// Send the request
axios.get(`${BEACON_PROVIDER_URL}/eth/v2/beacon/blocks/${BLOCK_ID}`, { headers: HEADER })
.then(response => {
// Parse the response and log the result.
try {
const parsedJson = response.data;
const slot = parsedJson.data.message.slot;
const randao = parsedJson.data.message.body.randao_reveal;
console.log(`randao value for slot ${slot} is: ${randao}`);
} catch (error) {
console.error(`An error occurred while parsing the response: ${error}`);
}
})
.catch(error => {
console.error(`An error occurred while fetching the data: ${error}`);
});
$ node index
randao value for slot 5717752 is:
0x91bed944631c3178c3c3d2ba2b981b12fc68bfc22e66c7f77477416f9f46837b15ae6cd6feb4347484c83e83751c7cab0bf93e39698eb61ab38fff51727a03a04ee1fa427162fc9539e647619be88b8bb0db37f7d241883371dca99fa049a2be
const axios = require('axios');
// Declare the beacon provider URL and request parameters.
const BEACON_PROVIDER_URL = "CHAINSTACK_BEACON_URL";
const HEADER = { 'Content-Type': 'application/json' };
const BLOCK_ID = "head";
// Send the request
axios.get(`${BEACON_PROVIDER_URL}/eth/v2/beacon/blocks/${BLOCK_ID}`, { headers: HEADER })
.then(response => {
// Parse the response and log the result.
try {
const parsedJson = response.data;
const slot = parsedJson.data.message.slot;
const randao = parsedJson.data.message.body.randao_reveal;
console.log(`randao value for slot ${slot} is: ${randao}`);
} catch (error) {
console.error(`An error occurred while parsing the response: ${error}`);
}
})
.catch(error => {
console.error(`An error occurred while fetching the data: ${error}`);
});
$ node index
randao value for slot 5717752 is:
0x91bed944631c3178c3c3d2ba2b981b12fc68bfc22e66c7f77477416f9f46837b15ae6cd6feb4347484c83e83751c7cab0bf93e39698eb61ab38fff51727a03a04ee1fa427162fc9539e647619be88b8bb0db37f7d241883371dca99fa049a2be