outgoingMessage.setHeaders(headers)

• headers <Headers> | <Map>
• 返回：<this>

为隐式头设置多个头值。headers 必须是 Headers 的实例或 Map，如果待发送的头中已经存在该头，它的值将被替换。

【Sets multiple header values for implicit headers. headers must be an instance of Headers or Map, if a header already exists in the to-be-sent headers, its value will be replaced.】

const headers = new Headers({ foo: 'bar' });
outgoingMessage.setHeaders(headers); 拷贝

或者

【or】

const headers = new Map([['foo', 'bar']]);
outgoingMessage.setHeaders(headers); 拷贝

当使用 outgoingMessage.setHeaders() 设置了头信息时，它们会与传递给 response.writeHead() 的任何头信息合并，并且传递给 response.writeHead() 的头信息具有优先权。

【When headers have been set with outgoingMessage.setHeaders(), they will be merged with any headers passed to response.writeHead(), with the headers passed to response.writeHead() given precedence.】

// Returns content-type = text/plain
const server = http.createServer((req, res) => {
  const headers = new Headers({ 'Content-Type': 'text/html' });
  res.setHeaders(headers);
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('ok');
}); 拷贝