use macro to generate headers

src/lib.rs

@@ -59,11 +59,7 @@ pub async fn handle_request_rs(req: Request) -> Response {
         return Response::new_with_opt_str_and_init(
             None, ResponseInit::new()
                 .status(200)
-                .headers({
-                    let headers = Headers::new().unwrap();
-                    cors!(headers);
-                    headers
-                }.as_ref())
+                .headers(headers!().add_cors().as_ref())
         ).unwrap();
     }
 

src/sn.rs

@@ -60,12 +60,9 @@ async fn get_actions(_req: Request, url: Url) -> MyResult<Response> {
         Some(&serde_json::to_string(&info).internal_err()?),
         ResponseInit::new()
             .status(200)
-            .headers({
-                let headers = Headers::new().unwrap();
-                 headers.set("Content-Type", "application/json").unwrap();
-                cors!(headers);
-                headers
-            }.as_ref())
+            .headers(headers!{
+                "Content-Type" => "application/json"
+            }.add_cors().as_ref())
     ).internal_err()
 }
 

src/utils.rs

@@ -1,5 +1,6 @@
 use cfg_if::cfg_if;
 use serde::Deserialize;
+use web_sys::Headers;
 
 cfg_if! {
     // When the `console_error_panic_hook` feature is enabled, we can call the
@@ -25,6 +26,33 @@ macro_rules! cors {
     };
 }
 
+// Adapted from <https://stackoverflow.com/questions/27582739/how-do-i-create-a-hashmap-literal>
+#[macro_export]
+macro_rules! headers(
+    { $($key:expr => $value:expr),+ } => {
+        {
+            let headers = ::web_sys::Headers::new().unwrap();
+            $(
+                headers.set($key, $value).unwrap();
+            )+
+            headers
+        }
+     };
+     () => { ::web_sys::Headers::new().unwrap() };
+);
+
+pub trait HeadersExt {
+    fn add_cors(self) -> Self;
+}
+
+impl HeadersExt for Headers {
+    fn add_cors(self) -> Self {
+        self.set("Access-Control-Allow-Origin", "*").unwrap();
+        self.set("Access-Control-Allow-Headers", "*").unwrap();
+        self
+    }
+}
+
 pub trait ResultExt<T, E> {
     // Ignore any error and return InternalError for them all
     // Used in place of ugly `.unwrap()`.