fix searching fulltext with tags, closes #4661

Author: zadam

src/services/search/expressions/note_content_fulltext.js

@@ -111,18 +111,31 @@ class NoteContentFulltextExp extends Expression {
 
         if (type === 'text' && mime === 'text/html') {
             if (!this.raw && content.length < 20000) { // striptags is slow for very large notes
-                // allow link to preserve URLs: https://github.com/zadam/trilium/issues/2412
-                content = striptags(content, ['a'], ' ');
-
-                // at least the closing tag can be easily stripped
-                content = content.replace(/<\/a>/ig, "");
+                content = this.stripTags(content);
             }
 
             content = content.replace(/&nbsp;/g, ' ');
         }
 
         return content.trim();
     }
+
+    stripTags(content) {
+        // we want to allow link to preserve URLs: https://github.com/zadam/trilium/issues/2412
+        // we want to insert space in place of block tags (because they imply text separation)
+        // but we don't want to insert text for typical formatting inline tags which can occur within one word
+        const linkTag = 'a';
+        const inlineFormattingTags = ['b', 'strong', 'em', 'i', 'span', 'big', 'small', 'font', 'sub', 'sup'];
+
+        // replace tags which imply text separation with a space
+        content = striptags(content, [linkTag, ...inlineFormattingTags], ' ');
+
+        // replace the inline formatting tags (but not links) without a space
+        content = striptags(content, [linkTag], '');
+
+        // at least the closing link tag can be easily stripped
+        return content.replace(/<\/a>/ig, "");
+    }
 }
 
 module.exports = NoteContentFulltextExp;