feat(express-middlewares): add UseHeader.Append decorator

express-middlewares/README.MD

@@ -179,6 +179,8 @@ Use **[HTTP status enums](https://github.com/jeremyben/tshttp/tree/master/status
 
 ## Response headers
 
+### Set headers
+
 > 🔦 `@UseHeader(header, value)|(headers)`<br>
 > 💫 Related Express method: [`res.set`](https://expressjs.com/en/4x/api.html#res.set)
 
@@ -205,6 +207,17 @@ class Controller {
 
 Use **[HTTP response headers enum](https://github.com/jeremyben/tshttp/tree/master/header)** from the same maintainer for an even better developer experience.
 
+### Append header value
+
+> 🔦 `@UseHeader.Append(header, value)`<br>
+> 💫 Related Express method: [`res.set`](https://expressjs.com/en/4x/api.html#res.append)
+
+Appends the specified `value` to the HTTP response header `field`. If the header is not already set, it creates the header with the specified `value`.
+
+```ts
+@UseHeader.Append('link', ['<http://localhost/>', '<http://localhost:3000/>'])
+```
+
 ## Response type
 
 > 🔦 `@UseType(contentType)`<br>

express-middlewares/src/response-headers-decorators.ts

@@ -30,6 +30,28 @@ export function UseHeader(field: string | ResponseHeaders, value?: string) {
 	})
 }
 
+export namespace UseHeader {
+	/**
+	 * Appends the specified `value` to the HTTP response header `field`.
+	 * @see https://expressjs.com/fr/api.html#res.append
+	 * @example
+	 * ```ts
+	 * ＠UseHeader.Append('link', ['<http://localhost/>', '<http://localhost:3000/>'])
+	 * ```
+	 * ------
+	 * @public
+	 */
+	export function Append<H extends string = ResponseHeaderName>(
+		field: H extends ResponseHeaderName ? ResponseHeaderName : string,
+		value: string | string[]
+	) {
+		return Use((req, res, next) => {
+			res.append(field, value)
+			next()
+		})
+	}
+}
+
 /**
  * Sets the `Content-Type` HTTP header to the specified MIME type.
  * @see https://expressjs.com/en/api.html#res.type