FetchRequestDelegate#{additional,prepare}HeadersForRequest()

src/core/drive/form_submission.ts

@@ -104,16 +104,14 @@ export class FormSubmission {
 
   // Fetch request delegate
 
-  additionalHeadersForRequest(request: FetchRequest, headers: { [header: string]: string }) {
-    const additionalHeaders: FetchRequestHeaders = {}
+  prepareHeadersForRequest(headers: FetchRequestHeaders, request: FetchRequest) {
     if (!request.isIdempotent) {
       const token = getCookieValue(getMetaContent("csrf-param")) || getMetaContent("csrf-token")
       if (token) {
-        additionalHeaders["X-CSRF-Token"] = token
+        headers["X-CSRF-Token"] = token
       }
-      additionalHeaders["Accept"] = [ StreamMessage.contentType, headers.Accept ].join(", ")
+      headers["Accept"] = [ StreamMessage.contentType, headers["Accept"] ].join(", ")
     }
-    return additionalHeaders
   }
 
   requestStarted(request: FetchRequest) {

src/core/frames/frame_controller.ts

@@ -1,5 +1,5 @@
 import { FrameElement, FrameElementDelegate, FrameLoadingStyle } from "../../elements/frame_element"
-import { FetchMethod, FetchRequest, FetchRequestDelegate } from "../../http/fetch_request"
+import { FetchMethod, FetchRequest, FetchRequestDelegate, FetchRequestHeaders } from "../../http/fetch_request"
 import { FetchResponse } from "../../http/fetch_response"
 import { AppearanceObserver, AppearanceObserverDelegate } from "../../observers/appearance_observer"
 import { parseHTMLDocument } from "../../util"
@@ -124,8 +124,8 @@ export class FrameController implements AppearanceObserverDelegate, FetchRequest
 
   // Fetch request delegate
 
-  additionalHeadersForRequest(request: FetchRequest) {
-    return { "Turbo-Frame": this.id }
+  prepareHeadersForRequest(headers: FetchRequestHeaders, request: FetchRequest) {
+    headers["Turbo-Frame"] = this.id
   }
 
   requestStarted(request: FetchRequest) {

src/http/fetch_request.ts

@@ -2,7 +2,7 @@ import { FetchResponse } from "./fetch_response"
 import { dispatch } from "../util"
 
 export interface FetchRequestDelegate {
-  additionalHeadersForRequest?(request: FetchRequest, headers: { [header: string]: string }): { [header: string]: string }
+  prepareHeadersForRequest?(headers: FetchRequestHeaders, request: FetchRequest): void
   requestStarted(request: FetchRequest): void
   requestPreventedHandlingResponse(request: FetchRequest, response: FetchResponse): void
   requestSucceededWithResponse(request: FetchRequest, response: FetchResponse): void
@@ -117,23 +117,22 @@ export class FetchRequest {
   }
 
   get headers() {
-    const defaultHeaders = { "Accept": "text/html, application/xhtml+xml" }
-    const additionalHeaders = this.additionalHeadersWithDefaults(defaultHeaders)
-
-    return { ...defaultHeaders, ...additionalHeaders }
-  }
-
-  additionalHeadersWithDefaults(defaults: { [header: string]: string }) {
-    if (typeof this.delegate.additionalHeadersForRequest == "function") {
-      return this.delegate.additionalHeadersForRequest(this, { ...defaults })
-    } else {
-      return {}
+    const headers = { ...this.defaultHeaders }
+    if (typeof this.delegate.prepareHeadersForRequest == "function") {
+      this.delegate.prepareHeadersForRequest(headers, this)
     }
+    return headers
   }
 
   get abortSignal() {
     return this.abortController.signal
   }
+
+  get defaultHeaders() {
+    return {
+      "Accept": "text/html, application/xhtml+xml"
+    }
+  }
 }
 
 function mergeFormDataEntries(url: URL, entries: [string, FormDataEntryValue][]): URL {