add trsuted-replace-fetch-response scriptlet

src/scriptlets/trusted-replace-fetch-response.js

@@ -0,0 +1,172 @@
+import {
+    hit,
+    getFetchData,
+    objectToString,
+    parseMatchProps,
+    validateParsedData,
+    getMatchPropsData,
+    noopPromiseResolve,
+    getWildcardSymbol,
+    // following helpers should be imported and injected
+    // because they are used by helpers above
+    toRegExp,
+    isValidStrPattern,
+    escapeRegExp,
+    isEmptyObject,
+    getRequestData,
+    getObjectEntries,
+    getObjectFromEntries,
+} from '../helpers/index';
+
+/* eslint-disable max-len */
+/**
+ * @scriptlet trusted-replace-fetch-response
+ *
+ * @description // FIXME
+ * Prevents `fetch` calls if **all** given parameters match
+ *
+ * Related UBO scriptlet:
+ * https://github.com/gorhill/uBlock/wiki/Resources-Library#no-fetch-ifjs-
+ *
+ * **Syntax**
+ * ```
+ * example.org#%#//scriptlet('prevent-fetch'[, propsToMatch[, responseBody]])
+ * ```
+ *
+ * - `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
+ *   - 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:
+ *    - `emptyObj` - empty object
+ *    - `emptyArr` - empty array
+ * > Usage with no arguments will log fetch calls to browser console;
+ * which is useful for debugging but permitted for production filter lists.
+ *
+ * **Examples**
+ * 1. Log all fetch calls
+ *     ```
+ *     example.org#%#//scriptlet('prevent-fetch')
+ *     ```
+ *
+ * 2. Prevent all fetch calls
+ *     ```
+ *     example.org#%#//scriptlet('prevent-fetch', '*')
+ *     OR
+ *     example.org#%#//scriptlet('prevent-fetch', '')
+ *     ```
+ *
+ * 3. Prevent fetch call for specific url
+ *     ```
+ *     example.org#%#//scriptlet('prevent-fetch', '/url\\.part/')
+ *     ```
+ *
+ * 4. Prevent fetch call for specific request method
+ *     ```
+ *     example.org#%#//scriptlet('prevent-fetch', 'method:HEAD')
+ *     ```
+ *
+ * 5. Prevent fetch call for specific url and request method
+ *     ```
+ *     example.org#%#//scriptlet('prevent-fetch', '/specified_url_part/ method:/HEAD|GET/')
+ *     ```
+ *
+ * 6. Prevent fetch call and specify response body value
+ *     ```
+ *     ! Specify response body for fetch call to a specific url
+ *     example.org#%#//scriptlet('prevent-fetch', '/specified_url_part/ method:/HEAD|GET/', 'emptyArr')
+ *
+ *     ! Specify response body for all fetch calls
+ *     example.org#%#//scriptlet('prevent-fetch', '', 'emptyArr')
+ *     ```
+ */
+/* eslint-enable max-len */
+export function trustedReplaceFetchResponse(source, pattern = '', replacement = '', propsToMatch = '') {
+    // 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
+    if (typeof fetch === 'undefined'
+        || typeof Proxy === 'undefined'
+        || typeof Response === 'undefined') {
+        return;
+    }
+
+    if (typeof pattern === 'undefined' || typeof replacement === 'undefined') {
+        return;
+    }
+
+    // eslint-disable-next-line no-console
+    const log = console.log.bind(console);
+    const nativeFetch = window.fetch;
+
+    let shouldPrevent = false;
+    let fetchData;
+
+    const handlerWrapper = (target, thisArg, args) => {
+        fetchData = getFetchData(args);
+
+        if (typeof propsToMatch === 'undefined') {
+            // log if no propsToMatch given
+            const logMessage = `log: fetch( ${objectToString(fetchData)} )`;
+            log(source, logMessage);
+        } else if (propsToMatch === '' || propsToMatch === getWildcardSymbol()) {
+            // prevent all fetch calls
+            shouldPrevent = true;
+        } else {
+            const parsedData = parseMatchProps(propsToMatch);
+            if (!validateParsedData(parsedData)) {
+                // eslint-disable-next-line no-console
+                console.log(`Invalid parameter: ${propsToMatch}`);
+                shouldPrevent = false;
+            } else {
+                const matchData = getMatchPropsData(parsedData);
+                // prevent only if all props match
+                shouldPrevent = Object.keys(matchData)
+                    .every((matchKey) => {
+                        const matchValue = matchData[matchKey];
+                        return Object.prototype.hasOwnProperty.call(fetchData, matchKey)
+                        && matchValue.test(fetchData[matchKey]);
+                    });
+            }
+        }
+
+        if (shouldPrevent) {
+            // REPLACE CONTENT HERE
+
+
+            hit(source);
+        }
+
+        return Reflect.apply(target, thisArg, args);
+    };
+
+    const fetchHandler = {
+        apply: handlerWrapper,
+    };
+
+    fetch = new Proxy(fetch, fetchHandler); // eslint-disable-line no-global-assign
+}
+
+trustedReplaceFetchResponse.names = [
+    'trusted-replace-fetch-response',
+
+];
+
+trustedReplaceFetchResponse.injections = [
+    hit,
+    getFetchData,
+    objectToString,
+    parseMatchProps,
+    validateParsedData,
+    getMatchPropsData,
+    noopPromiseResolve,
+    getWildcardSymbol,
+    toRegExp,
+    isValidStrPattern,
+    escapeRegExp,
+    isEmptyObject,
+    getRequestData,
+    getObjectEntries,
+    getObjectFromEntries,
+];