crypto.randomFill(buffer[, offset][, size], callback)

• buffer <Buffer> | <TypedArray> | <DataView> 必须提供。
• offset <number> 默认值: 0
• size <number> 默认值: buffer.length - offset
• callback <Function> function(err, buf) {}.

此函数类似于 crypto.randomBytes()，但要求第一个参数是将被填充的 Buffer。 它还要求传入回调。

如果未提供 callback 函数，则会抛出错误。

const buf = Buffer.alloc(10);
crypto.randomFill(buf, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

crypto.randomFill(buf, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

// 以上等价于以下内容：
crypto.randomFill(buf, 5, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

任何 TypedArray 或 DataView 实例都可以作为 buffer 传入。

const a = new Uint32Array(10);
crypto.randomFill(a, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const b = new Float64Array(10);
crypto.randomFill(b, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const c = new DataView(new ArrayBuffer(10));
crypto.randomFill(c, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

此 API 使用 libuv 的线程池，这对某些应用程序可能会产生意外的负面性能影响；有关更多信息，请参阅 UV_THREADPOOL_SIZE 文档。

crypto.randomFill() 的异步版本是在单个线程池请求中执行的。 为了最大限度地减少线程池任务长度变化，在执行客户端请求时将大型 randomFill 请求分区。

• buffer <Buffer> | <TypedArray> | <DataView> Must be supplied.
• offset <number> Default: 0
• size <number> Default: buffer.length - offset
• callback <Function> function(err, buf) {}.

This function is similar to crypto.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.

const buf = Buffer.alloc(10);
crypto.randomFill(buf, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

crypto.randomFill(buf, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

// The above is equivalent to the following:
crypto.randomFill(buf, 5, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

Any TypedArray or DataView instance may be passed as buffer.

const a = new Uint32Array(10);
crypto.randomFill(a, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const b = new Float64Array(10);
crypto.randomFill(b, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const c = new DataView(new ArrayBuffer(10));
crypto.randomFill(c, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .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.