The crypto.randomBytes() generates cyprtographically strong pseudo-random data. This method will not be completed until there is sufficient entropy in the bytes created. But even after this it does not takes more than a few milliseconds. This method basically creates a few random bytes which are further used.
Syntax
crypto.randomBytes(size, [callback])
Parameters
The above parameters are described as below −
size – This argument defines the number of bytes to be generated. Size must not be greater than 2**31 – 1.
callback – The callback is called if any error occurs in the method.
Example
Create a file with name – randomBytes.js and copy the below code snippet. After creating file, use the following command to run this code as shown in the example below −
node randomBytes.js
randomBytes.js
// crypto.randomBytes() Asynchronous demo example
// Importing the crypto module
const crypto = require('crypto');
crypto.randomBytes(64, (err, buf) => {
if (err) throw err;
console.log(`${buf.length} bytes of random data: ${buf.toString('hex')}`);
});Output
C:\home\node>> node randomBytes.js 64 bytes of random data: eb2bcebb999407286caea729998e7fa0c089178f8ca43857e73ea3ff66dbe1852af24a4b0199be 9192798a3f8ad6d6475db3621cfacf38dcb0fba5d77d73aaf5
Example
Let's take a look at one more example.
// crypto.randomBytes() Synchronous demo example
// Importing the crypto module
const crypto = require('crypto');
const buffer = crypto.randomBytes(256);
console.log(
`${buffer.length} bytes of random data: ${buffer.toString('base64')}`);Output
C:\home\node>> node randomBytes.js 256 bytes of random data: n7yfRMo/ujHfBWSF2VFdevG4WRbBoG9Fqwu51+/9ZBUV6Qo88YG7IbcEaIer+g+OgjMv4RyNQ6/67a F5xWmkOR3oA6J6bdAJ1pbstTuhIfItF1PQfP26YXk1QlaoKy/YJxPUngyK4kNG9O04aret4D+2qIq9 BUaQcv+R9Xi014VKNUDZ+YQKEaLHBhJMq6JgehJ56iNbdNJ4+PN7SQwjNdZ8gS76izAwYsSZ7Kuyx2 VzdXIKsLmjleuJ2DZ7/6Yyn8WM9463dhuh0KQ5nwFbgzucvjmdvDjBlGFZBGlKs6AXqYh+0Oe6Ckkv 3OpnXOJs+GExbmnvjaeDQ03khpdJfA==