people: Improve mentioning users with diacritics in their name.

This makes it possible to mention a user with a name like Gaël that
contains diacritics by typing e.g. "Gael", significantly reducing the
need to use a special keyboard to mention other users.

Fixes #11183.

frontend_tests/node_tests/composebox_typeahead.js

@@ -197,12 +197,19 @@ var twin2 = {
     email: 'twin2@zulip.com',
 };
 
+var gael = {
+    full_name: 'Gaël Twin',
+    user_id: 107,
+    email: 'twin3@zulip.com',
+};
+
 global.people.add_in_realm(hamlet);
 global.people.add_in_realm(othello);
 global.people.add_in_realm(cordelia);
 global.people.add_in_realm(lear);
 global.people.add_in_realm(twin1);
 global.people.add_in_realm(twin2);
+global.people.add_in_realm(gael);
 global.people.add(deactivated_user);
 
 var hamletcharacters = {
@@ -529,7 +536,7 @@ run_test('initialize', () => {
         // This should match the users added at the beginning of this test file.
         var actual_value = options.source();
         var expected_value = [hamlet, othello, cordelia, lear,
-                              twin1, twin2, hamletcharacters, backend];
+                              twin1, twin2, gael, hamletcharacters, backend];
         assert.deepEqual(actual_value, expected_value);
 
         // Even though the items passed to .highlighter() are the full
@@ -560,6 +567,15 @@ run_test('initialize', () => {
         assert.equal(options.matcher(othello), false);
         assert.equal(options.matcher(cordelia), false);
 
+        options.query = 'gael';
+        assert.equal(options.matcher(gael), true);
+
+        options.query = 'Gaël';
+        assert.equal(options.matcher(gael), true);
+
+        options.query = 'gaël';
+        assert.equal(options.matcher(gael), true);
+
         // Don't make suggestions if the last name only has whitespaces
         // (we're between typing names).
         options.query = 'othello@zulip.com,     ';

static/js/composebox_typeahead.js

@@ -50,6 +50,8 @@ function query_matches_language(query, lang) {
 }
 
 function query_matches_string(query, source_str, split_char) {
+    source_str = people.remove_diacritics(source_str);
+    query = people.remove_diacritics(query);
     // When `abc ` with a space at the end is typed in a
     // contenteditable widget such as the composebox PM section, the
     // space at the end was a `no break-space (U+00A0)` instead of

static/js/people.js

@@ -739,7 +739,7 @@ exports.incr_recipient_count = function (user_id) {
 
 // Diacritic removal from:
 // https://stackoverflow.com/questions/18236208/perform-a-find-match-with-javascript-ignoring-special-language-characters-acce
-function remove_diacritics(s) {
+exports.remove_diacritics = function (s) {
     if (/^[a-z]+$/.test(s)) {
         return s;
     }
@@ -751,7 +751,7 @@ function remove_diacritics(s) {
         .replace(/[úùüû]/g, "u")
         .replace(/[ç]/g, "c")
         .replace(/[ñ]/g, "n");
-}
+};
 
 exports.person_matches_query = function (user, query) {
     var email = user.email.toLowerCase();
@@ -770,7 +770,7 @@ exports.person_matches_query = function (user, query) {
         return _.any(names, function (name) {
             if (is_ascii) {
                 // Only ignore diacritics if the query is plain ascii
-                name = remove_diacritics(name);
+                name = exports.remove_diacritics(name);
             }
             if (name.indexOf(termlet) === 0) {
                 return true;