modify original response by prevent-fetch. AG-20293 #297

Squashed commit of the following:

commit 5fb4979
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Thu May 11 18:46:34 2023 +0300

    use await instead of then

commit 4c4046c
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 20:42:44 2023 +0300

    mark startsWith() and endsWith() helpers as deprecated

commit c21eccc
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 20:37:37 2023 +0300

    improve responseType checking condition

commit 68f3b60
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 20:33:10 2023 +0300

    fix INPUT_JSON_PATH

commit 087f934
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 20:32:36 2023 +0300

    fix assert.async()

commit dc62a81
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 15:14:13 2023 +0300

    fix imports

commit 4423117
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 14:44:36 2023 +0300

    Revert "update babel/runtime"

    This reverts commit abab623.

commit bb234c4
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 14:42:45 2023 +0300

    improve invalid param error text

commit a1bd1da
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 14:36:00 2023 +0300

    update changelog

commit 5e4e47c
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 14:35:08 2023 +0300

    update changelog

commit 531ea12
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 14:19:55 2023 +0300

    modify original response by prevent-fetch

commit abab623
Author: Slava Leleka <v.leleka@adguard.com>
Date:   Wed May 10 14:16:37 2023 +0300

    update babel/runtime

CHANGELOG.md

@@ -6,24 +6,33 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- improved `prevent-fetch` — if `responseType` is not specified,
+  original response type is returned instead of `default` [#297](https://github.com/AdguardTeam/Scriptlets/issues/291)
+
 ### Fixed
 
-- issue with reloading website if `$now$`/`$currentDate$` value is used in `trusted-set-cookie-reload` scriptlet [#291](https://github.com/AdguardTeam/Scriptlets/issues/291)
+- website reloading if `$now$`/`$currentDate$` value is used
+  in `trusted-set-cookie-reload` scriptlet [#291](https://github.com/AdguardTeam/Scriptlets/issues/291)
 
 ## <a name="v1.9.7"></a> [v1.9.7] - 2023-03-14
 
 ### Added
 
-- ability for `trusted-click-element` scriptlet to click element if `cookie`/`localStorage` item doesn't exist [#298](https://github.com/AdguardTeam/Scriptlets/issues/298)
-- static delay between multiple clicks in `trusted-click-element` [#284](https://github.com/AdguardTeam/Scriptlets/issues/284)
+- ability for `trusted-click-element` scriptlet to click element
+  if `cookie`/`localStorage` item doesn't exist [#298](https://github.com/AdguardTeam/Scriptlets/issues/298)
+- static delay between multiple clicks in `trusted-click-element`
+  [#284](https://github.com/AdguardTeam/Scriptlets/issues/284)
 
 ### Changed
 
 - improved the `convertScriptletToAdg()` method — now it validates the input rule syntax if it is an ADG rule
 
 ### Fixed
 
-- issue with `MutationObserver.disconnect()` in `trusted-click-element` [#284](https://github.com/AdguardTeam/Scriptlets/issues/284)
+- issue with `MutationObserver.disconnect()`
+  in `trusted-click-element` [#284](https://github.com/AdguardTeam/Scriptlets/issues/284)
 
 
 ## <a name="v1.9.1"></a> [v1.9.1] - 2023-03-07
@@ -36,13 +45,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 
-- decreased the minimal value for the `boost` parameter to `0.001` for `adjust-setTimeout` and `adjust-setInterval` [#262](https://github.com/AdguardTeam/Scriptlets/issues/262)
+- decreased the minimal value for the `boost` parameter to `0.001`
+  for `adjust-setTimeout` and `adjust-setInterval` [#262](https://github.com/AdguardTeam/Scriptlets/issues/262)
 
 ### Fixed
 
-- `prevent-element-src-loading` throwing error if `thisArg` is `undefined` [#270](https://github.com/AdguardTeam/Scriptlets/issues/270)
+- `prevent-element-src-loading` throwing error
+  if `thisArg` is `undefined` [#270](https://github.com/AdguardTeam/Scriptlets/issues/270)
 - logging `null` in `json-prune` [#282](https://github.com/AdguardTeam/Scriptlets/issues/282)
-- `xml-prune` does not prune a request if `new Request()` is used and issue with throwing error while logging some requests [#289](https://github.com/AdguardTeam/Scriptlets/issues/289)
+- `xml-prune`: no pruning a request if `new Request()` is used,
+  throwing an error while logging some requests [#289](https://github.com/AdguardTeam/Scriptlets/issues/289)
 - improve performance of the `isValidScriptletName()` method
 
 
@@ -53,17 +65,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - new `trusted-set-constant` scriptlet [#137](https://github.com/AdguardTeam/Scriptlets/issues/137)
 - new `inject-css-in-shadow-dom` scriptlet [#267](https://github.com/AdguardTeam/Scriptlets/issues/267)
 - `throwFunc` and `noopCallbackFunc` prop values for `set-constant` scriptlet
-- `recreateIframeForSlot` method mock to `googletagservices-gpt` redirect [#259](https://github.com/AdguardTeam/Scriptlets/issues/259)
+- `recreateIframeForSlot` method mock
+  to `googletagservices-gpt` redirect [#259](https://github.com/AdguardTeam/Scriptlets/issues/259)
 
 ### Changed
 
-- add decimal delay matching for `prevent-setInterval` and `prevent-setTimeout` [#247](https://github.com/AdguardTeam/Scriptlets/issues/247)
+- add decimal delay matching for `prevent-setInterval` and `prevent-setTimeout`
+  [#247](https://github.com/AdguardTeam/Scriptlets/issues/247)
 - debug logging to include rule text when available
 - `getScriptletFunction` calls to throw error on unknown scriptlet names
 
 ### Fixed
 
-- `prevent-xhr` and `trusted-replace-xhr-response` closure bug on multiple requests [#261](https://github.com/AdguardTeam/Scriptlets/issues/261)
+- `prevent-xhr` and `trusted-replace-xhr-response` closure bug on multiple requests
+  [#261](https://github.com/AdguardTeam/Scriptlets/issues/261)
 - missing `googletagmanager-gtm` in compatibility table
 
 
@@ -83,22 +98,24 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
-- `prevent-addEventListener` and `log-addEventListener` loosing context when encountering already bound `.addEventListener`
+- `prevent-addEventListener` and `log-addEventListener` loosing context
+  when encountering already bound `.addEventListener`
 - `google-ima3` conversion
 
 
 ## <a name="v1.7.14"></a> [v1.7.14] - 2022-12-16
 
 ### Added
 
-* `set-constant` ADG→UBO conversion for [`emptyArr` and `emptyObj`](https://github.com/uBlockOrigin/uBlock-issues/issues/2411)
+- `set-constant` ADG→UBO conversion
+  for [`emptyArr` and `emptyObj`](https://github.com/uBlockOrigin/uBlock-issues/issues/2411)
 
 
 ## <a name="v1.7.13"></a> [v1.7.13] - 2022-12-13
 
 ### Fixed
 
-* `isEmptyObject` helper not counting `prototype` as an object property
+- `isEmptyObject` helper not counting `prototype` as an object property
 
 
 ## <a name="v1.7.10"></a> [v1.7.10] - 2022-12-07
@@ -110,7 +127,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - `set-cookie-reload` infinite page reloading [#265](https://github.com/AdguardTeam/Scriptlets/issues/265)
-- breakage of `prevent-element-src-loading` due to `window` getting into `apply` wrapper [#264](https://github.com/AdguardTeam/Scriptlets/issues/264)
+- breakage of `prevent-element-src-loading` due to `window` getting into `apply` wrapper
+  [#264](https://github.com/AdguardTeam/Scriptlets/issues/264)
 - spread of args bug at `getXhrData` call for `trusted-replace-xhr-response`
 - request properties array not being served to `getRequestData` and `parseMatchProps` helpers
 

src/helpers/index.js

@@ -14,6 +14,7 @@ export * from './open-shadow-dom-utils';
 export * from './prevent-utils';
 export * from './prevent-window-open-utils';
 export * from './regexp-utils';
+export * from './response-utils';
 export * from './request-utils';
 export * from './storage-utils';
 export * from './string-utils';

src/helpers/response-utils.js

@@ -0,0 +1,40 @@
+/**
+ * Modifies original response with the given replacement data.
+ *
+ * @param {Response} origResponse Original response.
+ * @param {Object} replacement Replacement data for response with possible keys:
+ * - `body`: optional, string, default to '{}';
+ * - `type`: optional, string, original response type is used if not specified.
+ *
+ * @returns {Response} Modified response.
+ */
+export const modifyResponse = (
+    origResponse,
+    replacement = {
+        body: '{}',
+    },
+) => {
+    const headers = {};
+    origResponse?.headers?.forEach((value, key) => {
+        headers[key] = value;
+    });
+
+    const modifiedResponse = new Response(replacement.body, {
+        status: origResponse.status,
+        statusText: origResponse.statusText,
+        headers,
+    });
+
+    // Mock response url and type to avoid adblocker detection
+    // https://github.com/AdguardTeam/Scriptlets/issues/216
+    Object.defineProperties(modifiedResponse, {
+        url: {
+            value: origResponse.url,
+        },
+        type: {
+            value: replacement.type || origResponse.type,
+        },
+    });
+
+    return modifiedResponse;
+};

src/helpers/string-utils.js

@@ -90,6 +90,8 @@ export const getBeforeRegExp = (str, rx) => {
 /**
  * Checks whether the string starts with the substring
  *
+ * @deprecated use String.prototype.startsWith() instead. AG-18883
+ *
  * @param {string} str full string
  * @param {string} prefix substring
  * @returns {boolean} if string start with the substring
@@ -103,6 +105,8 @@ export const startsWith = (str, prefix) => {
 /**
  * Checks whether the string ends with the substring
  *
+ * @deprecated use String.prototype.endsWith() instead. AG-18883
+ *
  * @param {string} str full string
  * @param {string} ending substring
  * @returns {boolean} string ends with the substring

src/scriptlets/prevent-fetch.js

@@ -2,9 +2,9 @@ import {
     hit,
     getFetchData,
     objectToString,
-    noopPromiseResolve,
     matchRequestProps,
     logMessage,
+    modifyResponse,
     // following helpers should be imported and injected
     // because they are used by helpers above
     toRegExp,
@@ -24,7 +24,7 @@ import {
 /**
  * @scriptlet prevent-fetch
  * @description
- * Prevents `fetch` calls if **all** given parameters match
+ * Prevents `fetch` calls if **all** given parameters match.
  *
  * Related UBO scriptlet:
  * https://github.com/gorhill/uBlock/wiki/Resources-Library#no-fetch-ifjs-
@@ -35,14 +35,18 @@ import {
  * ```
  *
  * - `propsToMatch` — optional, string of space-separated properties to match; possible props:
- *   - string or regular expression for matching the URL passed to fetch call; empty string, wildcard `*` or invalid regular expression will match all fetch calls
+ *   - string or regular expression for matching the URL passed to fetch call;
+ *     empty string, wildcard `*` or invalid regular expression will match all fetch calls
  *   - colon-separated pairs `name:value` where
  *     - `name` is [`init` option name](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#parameters)
- *     - `value` is string or regular expression for matching the value of the option passed to fetch call; invalid regular expression will cause any value matching
- * - `responseBody` — optional, string for defining response body value, defaults to `emptyObj`. Possible values:
+ *     - `value` is string or regular expression for matching the value of the option passed to fetch call;
+ *       invalid regular expression will cause any value matching
+ * - `responseBody` — optional, string for defining response body value,
+ *   defaults to `emptyObj`. Possible values:
  *    - `emptyObj` — empty object
  *    - `emptyArr` — empty array
- * - `responseType` — optional, string for defining response type, defaults to `default`. Possible values:
+ * - `responseType` — optional, string for defining response type,
+ * original response type is used if not specified. Possible values:
  *    - `default`
  *    - `opaque`
  *
@@ -92,7 +96,7 @@ import {
  *     ```
  */
 /* eslint-enable max-len */
-export function preventFetch(source, propsToMatch, responseBody = 'emptyObj', responseType = 'default') {
+export function preventFetch(source, propsToMatch, responseBody = 'emptyObj', responseType) {
     // do nothing if browser does not support fetch or Proxy (e.g. Internet Explorer)
     // https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch
     // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy
@@ -108,16 +112,27 @@ export function preventFetch(source, propsToMatch, responseBody = 'emptyObj', re
     } else if (responseBody === 'emptyArr') {
         strResponseBody = '[]';
     } else {
+        logMessage(source, `Invalid responseBody parameter: '${responseBody}'`);
         return;
     }
 
-    // Skip disallowed response types
-    if (!(responseType === 'default' || responseType === 'opaque')) {
-        logMessage(source, `Invalid parameter: ${responseType}`);
+    const isResponseTypeSpecified = typeof responseType !== 'undefined';
+    const isResponseTypeSupported = (responseType) => {
+        const SUPPORTED_TYPES = [
+            'default',
+            'opaque',
+        ];
+        return SUPPORTED_TYPES.includes(responseType);
+    };
+    // Skip disallowed response types,
+    // specified responseType has limited list of possible values
+    if (isResponseTypeSpecified
+        && !isResponseTypeSupported(responseType)) {
+        logMessage(source, `Invalid responseType parameter: '${responseType}'`);
         return;
     }
 
-    const handlerWrapper = (target, thisArg, args) => {
+    const handlerWrapper = async (target, thisArg, args) => {
         let shouldPrevent = false;
         const fetchData = getFetchData(args);
         if (typeof propsToMatch === 'undefined') {
@@ -130,7 +145,14 @@ export function preventFetch(source, propsToMatch, responseBody = 'emptyObj', re
 
         if (shouldPrevent) {
             hit(source);
-            return noopPromiseResolve(strResponseBody, fetchData.url, responseType);
+            const origResponse = await Reflect.apply(target, thisArg, args);
+            return modifyResponse(
+                origResponse,
+                {
+                    body: strResponseBody,
+                    type: responseType,
+                },
+            );
         }
 
         return Reflect.apply(target, thisArg, args);
@@ -155,9 +177,9 @@ preventFetch.injections = [
     hit,
     getFetchData,
     objectToString,
-    noopPromiseResolve,
     matchRequestProps,
     logMessage,
+    modifyResponse,
     toRegExp,
     isValidStrPattern,
     escapeRegExp,