typeahead: Improve compose topic typeahead behaviour.

Fixes: #29006

We make the following changes:
* Do not show the typeahead menu when there are no matching topics.
* When the typeahead is not shown, pressing Tab in the topic field
should move the cursor to the compose box.
* When the typeahead is shown, pressing Tab should select the
currently focused option (as it does now), but put the cursor at
the end of the topic, rather than at the beginning.

web/e2e-tests/drafts.test.ts

@@ -40,14 +40,6 @@ async function create_stream_message_draft(page: Page): Promise<void> {
         content: "Test stream message.",
     });
     await page.type("#stream_message_recipient_topic", "tests", {delay: 100});
-
-    // Ideally, we don't need to click on the typeahead to create a draft with this topic but
-    // the typeahead seems bugged and remains open in the next compose session even after it
-    // is being closed via clicking on #compose_close.
-    const entry = await page.waitForSelector('.typeahead[style*="display: block"] .active a', {
-        visible: true,
-    });
-    await entry!.click();
     await page.click("#compose_close");
 }
 

web/e2e-tests/lib/common.ts

@@ -40,7 +40,7 @@ export const pm_recipient = {
         // input typeahead is different from the topic input
         // typeahead but both can be present in the DOM.
         const entry = await page.waitForSelector('.typeahead[style*="display: block"] .active a', {
-            visible: true,
+            visible: false,
         });
         await entry!.click();
     },

web/e2e-tests/mention.test.ts

@@ -12,12 +12,9 @@ async function test_mention(page: Page): Promise<void> {
     await page.waitForSelector("#compose", {visible: true});
 
     await common.select_stream_in_compose_via_dropdown(page, "Verona");
-    await common.select_item_via_typeahead(
-        page,
-        "#stream_message_recipient_topic",
-        "Test mention all",
-        "Test mention all",
-    );
+    await common.fill_form(page, 'form[action^="/json/messages"]', {
+        stream_message_recipient_topic: "Test mention all",
+    });
     await common.select_item_via_typeahead(page, "#compose-textarea", "@**all", "all");
     await common.ensure_enter_does_not_send(page);
 

web/src/bootstrap_typeahead.js

@@ -513,13 +513,20 @@ Typeahead.prototype = {
                 break;
 
             case 9: // tab
-                if (!this.options.tabIsEnter) {
-                    return;
-                }
-                if (!this.shown) {
+                // If the typeahead is not shown or tabIsEnter option is not set, do nothing and return
+                if (!this.options.tabIsEnter || !this.shown) {
                     return;
                 }
+
                 this.select(e);
+
+                if (e.currentTarget.id === "stream_message_recipient_topic") {
+                    // Move the cursor to the end of the topic
+                    const topic_length = this.$element.val().length;
+                    this.$element[0].selectionStart = topic_length;
+                    this.$element[0].selectionEnd = topic_length;
+                }
+
                 break;
 
             case 13: // enter

web/src/composebox_typeahead.js

@@ -1175,7 +1175,7 @@ export function initialize({on_enter_send}) {
         },
         sorter(items) {
             const sorted = typeahead_helper.sorter(this.query, items, (x) => x);
-            if (!sorted.includes(this.query)) {
+            if (sorted.length > 0 && !sorted.includes(this.query)) {
                 sorted.unshift(this.query);
             }
             return sorted;

web/tests/composebox_typeahead.test.js

@@ -812,7 +812,7 @@ test("initialize", ({override, override_rewire, mock_template}) => {
         // Suggest the query if this query doesn't match any existing topic.
         options.query = "non-existing-topic";
         actual_value = options.sorter([]);
-        expected_value = ["non-existing-topic"];
+        expected_value = [];
         assert.deepEqual(actual_value, expected_value);
 
         topic_typeahead_called = true;