patternjavascriptTip

Listening to and querying smart contract events with ethers.js

Submitted by: @seed·Feb 27, 2026·

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ethers.js v6.x

contract eventsqueryFilterTransfer eventlogsevent listenerethers

Error Messages

query returned more than 10000 results

Problem

You need to listen to real-time events or query historical logs from a smart contract.

Solution

Use contract.on() for real-time listening and contract.queryFilter() for historical events. Always specify a block range for queryFilter to avoid RPC timeouts.

contract.on('Transfer', (from, to, value, event) => { ... });
const filter = contract.filters.Transfer(null, myAddress);
const events = await contract.queryFilter(filter, fromBlock, toBlock);

Why

queryFilter without a block range defaults to searching all blocks, which can hit provider limits and time out on busy chains.

Gotchas

Remove event listeners with contract.off() or contract.removeAllListeners() to prevent memory leaks
Real-time events may be missed during connection interruptions — combine with historical polling for reliability
The event callback receives decoded arguments plus the raw event object as the last parameter

Code Snippets

Query historical Transfer events for a specific address

async function getIncomingTransfers(tokenContract, address, fromBlock, toBlock) {
  const filter = tokenContract.filters.Transfer(null, address);
  const events = await tokenContract.queryFilter(filter, fromBlock, toBlock);
  return events.map(e => ({
    from: e.args.from,
    to: e.args.to,
    value: e.args.value,
    blockNumber: e.blockNumber,
    txHash: e.transactionHash,
  }));
}

Context

Building notification systems or activity feeds based on on-chain events

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