What is backpressure in Node.js streams and how do you handle it?

Question

Accepted Answer

**Backpressure** occurs when a readable stream produces data faster than the writable stream can consume it.

**How it works:**
- writable.write() returns false when buffer is full.
- You should pause the readable stream.
- Resume when "drain" event fires.

```javascript
const readable = fs.createReadStream("big-file.txt");
const writable = fs.createWriteStream("output.txt");

readable.on("data", (chunk) => {
    const canContinue = writable.write(chunk);
    if (!canContinue) {
        readable.pause();
        writable.once("drain", () => readable.resume());
    }
});
```

**pipe() handles it automatically:**
```javascript
readable.pipe(writable);
```

**pipeline() is recommended (handles errors too):**
```javascript
const { pipeline } = require("stream");
pipeline(readable, writable, (err) => {
    if (err) console.error(err);
});
```

Node.js: What is backpressure in Node.js streams and how do you handle it?