fn_sig_ws.js

const WebSocket = require('ws');
const ws = new WebSocket('wss://ws.web3api.io', {headers: {x-api-key:'<api_key>'}});

// Events:
// addLiquidity 0x4d49e87d
// addLiquidityIbETHv2AlphaOptimal(uint256,uint256,uint256,address,uint256) 	0xe52bc129
// addLiquidityETHAlphaOptimal(uint256,uint256,address,uint256) 	0xb057e457
// addLiquidity(uint256) 	0x51c6590a

ws.on('open', () => {
  ws.send(JSON.stringify({
      jsonrpc: '2.0',
      method: 'subscribe',
      params: ["function", {"signature": "0x4d49e87d"}],
      id: 1,
    }));
});

ws.on('message', data => {
  console.log(JSON.stringify(JSON.parse(data), null, 2));
});