feat: support subtitle translate

src/injector.js

@@ -0,0 +1,50 @@
+import {
+  MSG_XHR_DATA_YOUTUBE,
+  MSG_GLOBAL_VAR_FETCH,
+  MSG_GLOBAL_VAR_BACK,
+} from "./config";
+
+// 响应window全局对象查询
+(function () {
+  window.addEventListener("message", (event) => {
+    if (
+      event.source === window &&
+      event.data &&
+      event.data.type === MSG_GLOBAL_VAR_FETCH
+    ) {
+      const { varName, requestId } = event.data;
+      if (varName) {
+        const value = window[varName];
+        window.postMessage(
+          {
+            type: MSG_GLOBAL_VAR_BACK,
+            payload: value,
+            requestId: requestId,
+          },
+          window.location.origin
+        );
+      }
+    }
+  });
+})();
+
+// 拦截字幕数据
+(function () {
+  const originalOpen = XMLHttpRequest.prototype.open;
+  XMLHttpRequest.prototype.open = function (...args) {
+    const url = args[1];
+    if (typeof url === "string" && url.includes("timedtext")) {
+      this.addEventListener("load", function () {
+        window.postMessage(
+          {
+            type: MSG_XHR_DATA_YOUTUBE,
+            url: this.responseURL,
+            response: this.responseText,
+          },
+          window.location.origin
+        );
+      });
+    }
+    return originalOpen.apply(this, args);
+  };
+})();