`Buffer.concat()`

Concatenates a list of buffers into a single new buffer.

Since Node 0.8 Spec ↗

Syntax

Buffer.concat(list[, totalLength])

Parameters

Name	Type	Required	Description
`list`	`Buffer[]`	Yes	An array of Buffer instances to join.
`totalLength`	`number`	No	Pre-computed total length; avoids an extra pass.

Returns

Buffer — A new Buffer containing all input bytes in order.

Examples

const a = Buffer.from('foo');
const b = Buffer.from('bar');
console.log(Buffer.concat([a, b]).toString());

Output

foobar

const chunks = [];
req.on('data', (c) => chunks.push(c));
req.on('end', () => {
  const body = Buffer.concat(chunks).toString();
  console.log(body.length);
});

Output

Notes

The standard way to assemble a body from streamed data chunks. Passing `totalLength` skips a length-summing pass for a minor speed gain. An empty list returns a zero-length buffer.