Node.js · Theory

What is the Poll phase in the Node.js event loop

Theory

198/723

What is the Poll phase in the Node.js event loop

the Poll phase in the Node.js event loop (what is) is a Node.js topic. In plain words you use it for wait for DB then reply in one Node process. Don’t start with a slogan — start with that picture.

Smallest example: async I/O, don’t block. Type it, run it, and say what you see. If you can do that from memory, you know the Poll phase in the Node.js event loop (what is).

From the example next to this theory — What is the Poll phase in the Node.

Trap — fs.readFileSync on a huge file. Fix that before you talk about advanced Node.js.

Viva — what is the Poll phase in the Node.js event loop (what is)? Then show async I/O, don’t block. Then name the trap.

Diagram

  request
      │
      ▼
  event loop
      │ I/O done
      ▼
  response

Exam tip

What is the Poll phase in the Node.js event loop (what is)? Show this: async I/O, don’t block. Trap: fs.readFileSync on a huge file.

Example

const EventEmitter = require("events");
const bus = new EventEmitter();

bus.on("ping", (n) => console.log("pong", n));
bus.emit("ping", 1);
bus.emit("ping", 2);

What is the Poll phase in the Node.js event loop — eventEmitter is the pub/sub core used across Node APIs.

Short notes

Defthe Poll phase in the Node.js event loop (what is) — wait for DB then reply in one Node process.
Ruleasync I/O, don’t block
Trapfs.readFileSync on a huge file
Useone Node process

Node.js · Theory

What is the Poll phase in the Node.js event loop

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Theory

198/723

What is the Poll phase in the Node.js event loop

Smallest example: async I/O, don’t block. Type it, run it, and say what you see. If you can do that from memory, you know the Poll phase in the Node.js event loop (what is).

From the example next to this theory — What is the Poll phase in the Node.

Trap — fs.readFileSync on a huge file. Fix that before you talk about advanced Node.js.

Viva — what is the Poll phase in the Node.js event loop (what is)? Then show async I/O, don’t block. Then name the trap.

Diagram

  request
      │
      ▼
  event loop
      │ I/O done
      ▼
  response

Exam tip

What is the Poll phase in the Node.js event loop (what is)? Show this: async I/O, don’t block. Trap: fs.readFileSync on a huge file.

Example

const EventEmitter = require("events");
const bus = new EventEmitter();

bus.on("ping", (n) => console.log("pong", n));
bus.emit("ping", 1);
bus.emit("ping", 2);

What is the Poll phase in the Node.js event loop — eventEmitter is the pub/sub core used across Node APIs.

Short notes

Defthe Poll phase in the Node.js event loop (what is) — wait for DB then reply in one Node process.
Ruleasync I/O, don’t block
Trapfs.readFileSync on a huge file
Useone Node process

What is the Poll phase in the Node.js event loop

Example

Short notes

Questions

What is the Poll phase in the Node.js event loop

Example

Short notes

Questions