fix block UI

app/src/main/java/io/legado/app/ui/book/read/ReadBookViewModel.kt

@@ -33,6 +33,8 @@ import io.legado.app.utils.postEvent
 import io.legado.app.utils.toStringArray
 import io.legado.app.utils.toastOnUi
 import kotlinx.coroutines.Dispatchers.IO
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 
 /**
  * 阅读界面数据处理
@@ -145,10 +147,13 @@ class ReadBookViewModel(application: Application) : BaseViewModel(application) {
             }
         } else {
             ReadBook.bookSource?.let {
+                viewModelScope.launch {
+                    withContext(IO) {
                         val preUpdateJs = it.ruleToc?.preUpdateJs
                         if (!preUpdateJs.isNullOrBlank()) {
                             AnalyzeRule(book, it).evalJS(preUpdateJs)
                         }
+                    }
                     WebBook.getChapterList(viewModelScope, it, book)
                         .onSuccess(IO) { cList ->
                             appDb.bookChapterDao.insert(*cList.toTypedArray())
@@ -162,6 +167,7 @@ class ReadBookViewModel(application: Application) : BaseViewModel(application) {
                 }
             }
         }
+    }
 
     /**
      * 同步进度