capitalizeTitle(): Handle HTML tags

https://forums.zotero.org/discussion/113653/zotero-7-beta-incorrect-behaviour-applying-title-case-action-to-titles-with-rich-text-markup

For `<i>Title case</i>`, return `<i>Title Case</i>` instead of `<i>title Case</I>`.

test/tests/utilitiesTest.js

@@ -291,7 +291,21 @@ describe("Zotero.Utilities", function() {
 			});
 		});
 	});
-
+
+	describe("#capitalizeTitle()", function () {
+		it("should capitalize within HTML tags", function () {
+			let input = 'Foo <b>bar</b> foo <em>bar</em>';
+			let expected = 'Foo <b>Bar</b> Foo <em>Bar</em>';
+			assert.equal(Zotero.Utilities.capitalizeTitle(input, true), expected);
+		});
+
+		it("shouldn't alter attributes within HTML tags", function () {
+			let input = 'Foo <span style="font-variant:small-caps;">bar</span> foo';
+			let expected = 'Foo <span style="font-variant:small-caps;">Bar</span> Foo';
+			assert.equal(Zotero.Utilities.capitalizeTitle(input, true), expected);
+		});
+	});
+
 	describe("walkNoteDOM()", function () {
 		it("should iterate subtrees in depth-first order and allow modifications", function () {
 			let html = loadTestData('note.html');

utilities.js

@@ -1042,9 +1042,16 @@ var Utilities = {
 		if (Zotero.Prefs && !Zotero.Prefs.get('capitalizeTitles') && !force) return string;
 		if (!string) return "";
 
+		// Remove HTML tags but remember their positions
+		let htmlTags = [];
+		let cleanedString = string.replace(/<[^>]+>/g, (match, offset) => {
+			htmlTags.push({ match, offset });
+			return "";
+		});
+
 		// split words
-		var words = string.split(delimiterRegexp);
-		var isUpperCase = string.toUpperCase() == string;
+		var words = cleanedString.split(delimiterRegexp);
+		var isUpperCase = cleanedString.toUpperCase() == cleanedString;
 
 		var newString = "";
 		var delimiterOffset = words[0].length;
@@ -1084,6 +1091,11 @@ var Utilities = {
 			newString += words[i];
 		}
 
+		// Reinsert HTML tags into their original positions
+		htmlTags.forEach(tag => {
+			newString = newString.substring(0, tag.offset) + tag.match + newString.substring(tag.offset);
+		});
+
 		return newString;
 	},