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writeEarlyHints

method ServerResponse.prototype.writeEarlyHints
Jump to headingServerResponse.prototype.writeEarlyHints(
hints: Record<string, string | string[]>,
callback?: () => void,
): void

Sends an HTTP/1.1 103 Early Hints message to the client with a Link header, indicating that the user agent can preload/preconnect the linked resources. The hints is an object containing the values of headers to be sent with early hints message. The optional callback argument will be called when the response message has been written.

Example

const earlyHintsLink = '</styles.css>; rel=preload; as=style';
response.writeEarlyHints({
  'link': earlyHintsLink,
});

const earlyHintsLinks = [
  '</styles.css>; rel=preload; as=style',
  '</scripts.js>; rel=preload; as=script',
];
response.writeEarlyHints({
  'link': earlyHintsLinks,
  'x-trace-id': 'id for diagnostics',
});

const earlyHintsCallback = () => console.log('early hints message sent');
response.writeEarlyHints({
  'link': earlyHintsLinks,
}, earlyHintsCallback);

Parameters Jump to heading

Jump to headinghints: Record<string, string | string[]>

An object containing the values of headers

optional
Jump to headingcallback: () => void

Will be called when the response message has been written

Return Type Jump to heading

void
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