node中response在触发end()的时候才会发数据到客户端吗？

var http = require('http');
var fs = require('fs');

var server = http.createServer(function (req, res) {
    var stream = fs.createReadStream(__dirname + '/data.txt');
    stream.pipe(res);
});
server.listen(8000);

这段代码是在stream-handbook中摘取的，带有下面这句解释：

now the data.txt file will be written to clients one chunk at a time immediately as they are received from the disk.

我的疑问是：response在接收到每一个小chunk之后，会立即发往客户端吗？不是在response.end时候才一起发往客户端的吗？ 如果是前者，那浏览器会怎么处理这些小chunk，会跟bigpipe的处理方式一样吗？