`fs.readFileSync()`

Synchronously reads the entire contents of a file, blocking the event loop.

Since Node 0.x Spec ↗

Syntax

fs.readFileSync(path[, options])

Parameters

Name	Type	Required	Description
`path`	`string \| Buffer \| URL \| integer`	Yes	The filename or file descriptor.
`options`	`object \| string`	No	Encoding string or object with `encoding` and `flag`.

Returns

string | Buffer — The file contents (string when an encoding is given).

Examples

import { readFileSync } from 'node:fs';

const pkg = JSON.parse(readFileSync('./package.json', 'utf8'));
console.log(pkg.name);

Output

my-app

import { readFileSync } from 'node:fs';

const key = readFileSync('./private.pem');
console.log(key.length, 'bytes');

Output

1704 bytes

Notes

Blocks the entire event loop until the read finishes, so use it only for startup config or CLI scripts, never inside request handlers. Throws synchronously on error; wrap in try/catch.