INNER CODE UNIT · JavaScript

monitorListingsUsingEventEmitter

mongodb-developer/nodejs-quickstart · changeStreams.js:81

async function monitorListingsUsingEventEmitter(client, timeInMs = 60000, pipeline = []) {
    const collection = client.db("sample_airbnb").collection("listingsAndReviews");

    // See https://mongodb.github.io/node-mongodb-native/3.6/api/Collection.html#watch for the watch() docs
    const changeStream = collection.watch(pipeline);

    // ChangeStream inherits from the Node Built-in Class EventEmitter (https://nodejs.org/dist/latest-v12.x/docs/api/events.html#events_class_eventemitter).
    // We can use EventEmitter's on() to add a listener function that will be called whenever a change occurs in the change stream.
    // See https://nodejs.org/dist/latest-v12.x/docs/api/events.html#events_emitter_on_eventname_listener for the on() docs.
    changeStream.on('change', (next) => {
        console.log(next);
    });

    // Wait the given amount of time and then close the change stream
    await closeChangeStream(timeInMs, changeStream);
}

/**

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