response.write(chunk[, encoding][, callback])

• chunk <string> | <Buffer>
• encoding <string> 默认值: 'utf8'
• callback <Function>
• 返回: <boolean>

如果此方法被调用且 response.writeHead() 还没被调用，则会切换到隐式的标头模式并刷新隐式的标头。

这会发送一块响应正文。 可以多次调用此方法以提供正文的连续部分。

在 http 模块中，当请求是 HEAD 请求时，响应正文会被省略。 同样，204 和 304 响应不得包含消息正文。

chunk 可以是字符串或缓冲区。 如果 chunk 是字符串，则第二个参数指定如何将其编码为字节流。 当刷新数据块时将调用 callback。

这是原始的 HTTP 正文，与可能使用的更高级别的多部分正文编码无关。

第一次调用 response.write() 时，它会将缓存的标头信息和正文的第一个块发送给客户端。 第二次调用 response.write() 时，Node.js 会假定数据将被流式传输，并单独发送新数据。 也就是说，响应被缓冲到正文的第一个块。

如果整个数据被成功刷新到内核缓冲区，则返回 true。 如果所有或部分数据在用户内存中排队，则返回 false。 当缓冲区再次空闲时，则将触发 'drain'。

• chunk <string> | <Buffer>
• encoding <string> Default: 'utf8'
• callback <Function>
• Returns: <boolean>

If this method is called and response.writeHead() has not been called, it will switch to implicit header mode and flush the implicit headers.

This sends a chunk of the response body. This method may be called multiple times to provide successive parts of the body.

In the http module, the response body is omitted when the request is a HEAD request. Similarly, the 204 and 304 responses must not include a message body.

chunk can be a string or a buffer. If chunk is a string, the second parameter specifies how to encode it into a byte stream. callback will be called when this chunk of data is flushed.

This is the raw HTTP body and has nothing to do with higher-level multi-part body encodings that may be used.

The first time response.write() is called, it will send the buffered header information and the first chunk of the body to the client. The second time response.write() is called, Node.js assumes data will be streamed, and sends the new data separately. That is, the response is buffered up to the first chunk of the body.

Returns true if the entire data was flushed successfully to the kernel buffer. Returns false if all or part of the data was queued in user memory. 'drain' will be emitted when the buffer is free again.