4 files changed, 27 insertions, 3 deletions
diff --git a/ext/js/background/backend.js b/ext/js/background/backend.js
index 484473c7..3d8c4c4a 100644
--- a/ext/js/background/backend.js
+++ b/ext/js/background/backend.js
@@ -127,7 +127,8 @@ class Backend {
             ['getOrCreateSearchPopup',       {async: true,  contentScript: true,  handler: this._onApiGetOrCreateSearchPopup.bind(this)}],
             ['isTabSearchPopup',             {async: true,  contentScript: true,  handler: this._onApiIsTabSearchPopup.bind(this)}],
             ['triggerDatabaseUpdated',       {async: false, contentScript: true,  handler: this._onApiTriggerDatabaseUpdated.bind(this)}],
-            ['testMecab',                    {async: true,  contentScript: true,  handler: this._onApiTestMecab.bind(this)}]
+            ['testMecab',                    {async: true,  contentScript: true,  handler: this._onApiTestMecab.bind(this)}],
+            ['textHasJapaneseCharacters',    {async: false, contentScript: true,  handler: this._onApiTextHasJapaneseCharacters.bind(this)}]
         ]);
         this._messageHandlersWithProgress = new Map([
         ]);
@@ -727,6 +728,10 @@ class Backend {
         return true;
     }
 
+    _onApiTextHasJapaneseCharacters({text}) {
+        return this._japaneseUtil.isStringPartiallyJapanese(text);
+    }
+
     // Command handlers
 
     async _onCommandOpenSearchPage(params) {
diff --git a/ext/js/comm/api.js b/ext/js/comm/api.js
index 472e464b..a2eb004c 100644
--- a/ext/js/comm/api.js
+++ b/ext/js/comm/api.js
@@ -168,6 +168,10 @@ class API {
         return this._invoke('testMecab', {});
     }
 
+    textHasJapaneseCharacters(text) {
+        return this._invoke('textHasJapaneseCharacters', {text});
+    }
+
     // Utilities
 
     _createActionPort(timeout=5000) {
diff --git a/ext/js/display/display.js b/ext/js/display/display.js
index ad9a25b4..8b521d21 100644
--- a/ext/js/display/display.js
+++ b/ext/js/display/display.js
@@ -543,7 +543,7 @@ class Display extends EventDispatcher {
                 case 'kanji':
                     {
                         let query = urlSearchParams.get('query');
-                        if (!query) { break; }
+                        if (query === null) { break; }
 
                         this._query = query;
                         clear = false;
@@ -882,7 +882,7 @@ class Display extends EventDispatcher {
 
         let {definitions} = content;
         if (!Array.isArray(definitions)) {
-            definitions = lookup ? await this._findDefinitions(isTerms, query, wildcardsEnabled, optionsContext) : [];
+            definitions = lookup && query.length > 0 ? await this._findDefinitions(isTerms, query, wildcardsEnabled, optionsContext) : [];
             if (this._setContentToken !== token) { return; }
             content.definitions = definitions;
             changeHistory = true;
diff --git a/ext/js/language/text-scanner.js b/ext/js/language/text-scanner.js
index 073b1a6c..4994faea 100644
--- a/ext/js/language/text-scanner.js
+++ b/ext/js/language/text-scanner.js
@@ -17,6 +17,7 @@
 
 /* global
  * DocumentUtil
+ * TextSourceElement
  */
 
 class TextScanner extends EventDispatcher {
@@ -321,6 +322,12 @@ class TextScanner extends EventDispatcher {
                 ({definitions, sentence, type} = result);
                 this._inputInfoCurrent = inputInfo;
                 this.setCurrentTextSource(textSource);
+            } else if (textSource instanceof TextSourceElement && await this._hasJapanese(textSource.fullContent)) {
+                definitions = [];
+                sentence = {sentence: '', offset: 0};
+                type = 'terms';
+                this._inputInfoCurrent = inputInfo;
+                this.setCurrentTextSource(textSource);
             }
         } catch (e) {
             error = e;
@@ -978,4 +985,12 @@ class TextScanner extends EventDispatcher {
             }
         }
     }
+
+    async _hasJapanese(text) {
+        try {
+            return await yomichan.api.textHasJapaneseCharacters(text);
+        } catch (e) {
+            return false;
+        }
+    }
 }