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A way to use the clearSubscriptions method is to place it in a timer to clear all of the subscriptions after a pre-determined about.The following code is an example using the subscribe(“newBlockHeaders”) method, which will be stopped and removed after one minute using clearSubscriptions:
const { ethers } = require("ethers");const NODE_URL = "CHAINSTACK_WSS_URL";const provider = new ethers.WebSocketProvider(NODE_URL);async function subscribeToNewBlocks() { try { // Listen for the 'block' event, emitted on every new block provider.on('block', handleNewBlock); console.log("Subscribed to new blocks"); } catch (error) { console.error(`Error subscribing to new blocks: ${error}`); }}/* Fallback functions to react to the different events */// Event listener that logs the received block numberasync function handleNewBlock(blockNumber) { const block = await provider.getBlock(blockNumber); console.log(block);}async function clearSubscriptions() { try { await provider.removeAllListeners(); console.log("Subscriptions were canceled successfully"); return process.exit(1) } catch (error) { console.error("Failed to cancel subscriptions:", error); return process.exit(1) }}async function main() { subscribeToNewBlocks(); // Run clearSubscriptions() once after 60 seconds setTimeout(clearSubscriptions, 60000);}main()
The code starts by defining an async function called subscribeToNewBlocks that subscribes to new blocks by registering a listener for the block event using the provider.on method. Each time a new block is mined, ethers.js emits the block number, and the handleNewBlock listener fetches the full block with provider.getBlock and logs it to the console.The subscribeToNewBlocks function is called from the main function, which is also defined in the code. The main function calls subscribeToNewBlocks to create a new subscription and then schedules the clearSubscriptions function to run once after 60 seconds using the setTimeout function. The clearSubscriptions function uses the provider.removeAllListeners method to cancel any existing subscriptions and log a message to the console if the cancellation was successful.
