method Http2ServerResponse.prototype.writeHead
Usage in Deno
```typescript import { Http2ServerResponse } from "node:node__http2.d.ts"; ```
Http2ServerResponse.prototype.writeHead(statusCode: number,headers?: OutgoingHttpHeaders,): this
Sends a response header to the request. The status code is a 3-digit HTTP
status code, like `404`. The last argument, `headers`, are the response headers.
Returns a reference to the `Http2ServerResponse`, so that calls can be chained.
For compatibility with `HTTP/1`, a human-readable `statusMessage` may be
passed as the second argument. However, because the `statusMessage` has no
meaning within HTTP/2, the argument will have no effect and a process warning
will be emitted.
```js
const body = 'hello world';
response.writeHead(200, {
'Content-Length': Buffer.byteLength(body),
'Content-Type': 'text/plain; charset=utf-8',
});
```
`Content-Length` is given in bytes not characters. The`Buffer.byteLength()` API may be used to determine the number of bytes in a
given encoding. On outbound messages, Node.js does not check if Content-Length
and the length of the body being transmitted are equal or not. However, when
receiving messages, Node.js will automatically reject messages when the `Content-Length` does not match the actual payload size.
This method may be called at most one time on a message before `response.end()` is called.
If `response.write()` or `response.end()` are called before calling
this, the implicit/mutable headers will be calculated and call this function.
When headers have been set with `response.setHeader()`, they will be merged
with any headers passed to `response.writeHead()`, with the headers passed
to `response.writeHead()` given precedence.
```js
// Returns content-type = text/plain
const server = http2.createServer((req, res) => {
res.setHeader('Content-Type', 'text/html; charset=utf-8');
res.setHeader('X-Foo', 'bar');
res.writeHead(200, { 'Content-Type': 'text/plain; charset=utf-8' });
res.end('ok');
});
```
Attempting to set a header field name or value that contains invalid characters
will result in a `TypeError` being thrown.
optional
headers: OutgoingHttpHeaders
this