node-redis/examples/blocking-list-pop.js

// This example shows how to use the blocking LPUSH command.

// This code shows how to run with isolation the blPop Command to block the script while waiting for a value to be pushed to the list.
// The script will be blocked until the LPUSH command is executed.
// After which we log the list and quit the client.

import { createClient, commandOptions } from 'redis';

const client = createClient();

await client.connect();

const keyName = 'keyName';

const blpopPromise = client.blPop(
  commandOptions({ isolated: true }),
  keyName,
  0
);

await client.lPush(keyName, 'value');

const listItem = await blpopPromise;

console.log('blpopPromise resolved');
// listItem will be:
// {"key":"keyName","element":"value"}
console.log(`listItem is '${JSON.stringify(listItem)}'`);

await client.quit();