Usage in Deno
import { randomFill } from "node:crypto";
randomFill<T extends ArrayBufferView>(buffer: T,callback: (err: Error | null,buf: T,) => void,): void
This function is similar to randomBytes but requires the first
argument to be a Buffer that will be filled. It also
requires that a callback is passed in.
If the callback function is not provided, an error will be thrown.
import { Buffer } from 'node:buffer';
const { randomFill } = await import('node:crypto');
const buf = Buffer.alloc(10);
randomFill(buf, (err, buf) => {
if (err) throw err;
console.log(buf.toString('hex'));
});
randomFill(buf, 5, (err, buf) => {
if (err) throw err;
console.log(buf.toString('hex'));
});
// The above is equivalent to the following:
randomFill(buf, 5, 5, (err, buf) => {
if (err) throw err;
console.log(buf.toString('hex'));
});
Any ArrayBuffer, TypedArray, or DataView instance may be passed as buffer.
While this includes instances of Float32Array and Float64Array, this
function should not be used to generate random floating-point numbers. The
result may contain +Infinity, -Infinity, and NaN, and even if the array
contains finite numbers only, they are not drawn from a uniform random
distribution and have no meaningful lower or upper bounds.
import { Buffer } from 'node:buffer';
const { randomFill } = await import('node:crypto');
const a = new Uint32Array(10);
randomFill(a, (err, buf) => {
if (err) throw err;
console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
.toString('hex'));
});
const b = new DataView(new ArrayBuffer(10));
randomFill(b, (err, buf) => {
if (err) throw err;
console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
.toString('hex'));
});
const c = new ArrayBuffer(10);
randomFill(c, (err, buf) => {
if (err) throw err;
console.log(Buffer.from(buf).toString('hex'));
});
This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the UV_THREADPOOL_SIZE documentation for more information.
The asynchronous version of crypto.randomFill() is carried out in a single
threadpool request. To minimize threadpool task length variation, partition
large randomFill requests when doing so as part of fulfilling a client
request.
void