function randomFill
Usage in Deno
```typescript import { randomFill } from "node:node__crypto.d.ts"; ```
randomFill<T extends ArrayBufferView>(buffer: T,callback: (err: Error | null,buf: T,) => void,): void
This function is similar to [randomBytes](../.././node__crypto.d.ts/~/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.
```js
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.
```js
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