Node.js · Theory

fs.writeFile() Method

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fs.writeFile() Method

Don’t start fs.writeFile() Method with jargon. Start with read a big CSV. That is the whole point.

Keep fs.writeFile() Method small. Kabir should finish read a big CSV in a few lines, not a 40-line dump.

Without fs.writeFile() Method, an upload job gets messy and read a big CSV is hard to trust.

Kabir ships fs.writeFile() Method in an upload job. That is the use case worth saying.

If read a big CSV breaks under fs.writeFile() Method, check loading the whole file into RAM first.

After fs.writeFile() Method, Kabir should still remember loading the whole file into RAM.

Close fs.writeFile() Method with — “If I skip it, read a big CSV goes wrong like this: loading the whole file into RAM.”

Exam tip

Board: read a big CSV. Dry-run fs.writeFile() Method. Name the trap: loading the whole file into RAM.

Example

const fs = require("fs");
const path = require("path");

const file = path.join(__dirname || ".", "demo.txt");
fs.writeFileSync(file, "hello node\n");
const text = fs.readFileSync(file, "utf8");
console.log(text.trim());
fs.unlinkSync(file);

fs.writeFile() Method — fs reads/writes files. Prefer promises/async APIs in real apps.

Short notes

Deffs.writeFile() Method — Kabir uses it for read a big CSV in an upload job.
Rulefs.writeFile() Method → createReadStream.
Rememberfs.writeFile() Method + the event loop (an upload job).
Usefs.writeFile() Method in an upload job (read a big CSV).
Trapfs.writeFile() Method — loading the whole file into RAM.
Exfs.writeFile() Method → read a big CSV.

const fs = require("fs"); const path = require("path"); const file = path.join(__dirname || ".", "demo.txt"); fs.writeFileSync(file, "hello node\n"); const text = fs.readFileSync(file, "utf8"); console.log(text.trim()); fs.unlinkSync(file);

fs.writeFile() Method

Example

Short notes

Questions

fs.writeFile() Method

Example

Short notes

Questions