compose: Fix recent autocomplete regression.

As part of giving the stream/topic fields in the
compose box longer ids, I broke the autocomplete
code that handles re-focusing the cursor after
a user hits enter.  The worst symptom of this was
that we tried to send a message before compose
finished (although it wouldn't fully deliver the
message).

The new code should be a bit easier to grep for
if we rename these fields again, as we explicitly
use selector syntax.

frontend_tests/node_tests/composebox_typeahead.js

@@ -828,7 +828,7 @@ run_test('initialize', () => {
     var event = {
         keyCode: 13,
         target: {
-            id: 'stream',
+            id: 'stream_message_recipient_stream',
         },
         preventDefault: noop,
     };
@@ -872,7 +872,7 @@ run_test('initialize', () => {
     $('#compose-textarea').caret = noop;
 
     event.keyCode = 13;
-    event.target.id = 'subject';
+    event.target.id = 'stream_message_recipient_topic';
     $('form#send_message_form').keydown(event);
     event.target.id = 'compose-textarea';
     page_params.enter_sends = false;
@@ -909,7 +909,7 @@ run_test('initialize', () => {
     event = {
         keyCode: 13,
         target: {
-            id: 'stream',
+            id: 'stream_message_recipient_stream',
         },
         preventDefault: noop,
     };

static/js/composebox_typeahead.js

@@ -115,31 +115,42 @@ function handle_keydown(e) {
     var code = e.keyCode || e.which;
 
     if (code === 13 || code === 9 && !e.shiftKey) { // Enter key or tab key
-        if (e.target.id === "stream" || e.target.id === "subject" || e.target.id === "private_message_recipient") {
+        var target_sel;
+
+        if (e.target.id) {
+            target_sel = '#' + e.target.id;
+        }
+
+        var on_stream = target_sel === "#stream_message_recipient_stream";
+        var on_topic = target_sel  === "#stream_message_recipient_topic";
+        var on_pm = target_sel === "#private_message_recipient";
+        var on_compose = target_sel === '#compose-textarea';
+
+        if (on_stream || on_topic || on_pm) {
             // For enter, prevent the form from submitting
             // For tab, prevent the focus from changing again
             e.preventDefault();
         }
 
         // In the compose_textarea box, preventDefault() for tab but not for enter
-        if (e.target.id === 'compose-textarea' && code !== 13) {
+        if (on_compose && code !== 13) {
             e.preventDefault();
         }
 
-        if (e.target.id === "stream") {
+        if (on_stream) {
-            nextFocus = "subject";
+            nextFocus = "#stream_message_recipient_topic";
-        } else if (e.target.id === "subject") {
+        } else if (on_topic) {
             if (code === 13) {
                 e.preventDefault();
             }
-            nextFocus = 'compose-textarea';
+            nextFocus = '#compose-textarea';
-        } else if (e.target.id === "private_message_recipient") {
+        } else if (on_pm) {
-            nextFocus = 'compose-textarea';
+            nextFocus = '#compose-textarea';
-        } else if (e.target.id === 'compose-textarea') {
+        } else if (on_compose) {
             if (code === 13) {
                 nextFocus = false;
             } else {
-                nextFocus = "compose-send-button";
+                nextFocus = "#compose-send-button";
             }
         } else {
             nextFocus = false;
@@ -159,11 +170,11 @@ function handle_keydown(e) {
             // takes the typeaheads a little time to open after the user finishes typing, which
             // can lead to the focus moving without the autocomplete having a chance to happen.
             if (nextFocus) {
-                ui_util.focus_on(nextFocus);
+                $(nextFocus).focus();
                 nextFocus = false;
             }
 
-            if (e.target.id === 'compose-textarea' && code === 13) {
+            if (on_compose && code === 13) {
                 var has_non_shift_modifier_key = e.ctrlKey || e.metaKey || e.altKey;
                 var has_modifier_key = e.shiftKey || has_non_shift_modifier_key;
                 var this_enter_sends;
@@ -230,7 +241,7 @@ function handle_keyup(e) {
     var code = e.keyCode || e.which;
     if (code === 13 || code === 9 && !e.shiftKey) { // Enter key or tab key
         if (nextFocus) {
-            ui_util.focus_on(nextFocus);
+            $(nextFocus).focus();
             nextFocus = false;
         }
     }

static/js/ui_util.js

@@ -9,16 +9,6 @@ exports.change_tab_to = function (tabname) {
     $('#gear-menu a[href="' + tabname + '"]').tab('show');
 };
 
-exports.focus_on = function (field_id) {
-    // Call after autocompleting on a field, to advance the focus to
-    // the next input field.
-
-    // Bootstrap's typeahead does not expose a callback for when an
-    // autocomplete selection has been made, so we have to do this
-    // manually.
-    $("#" + field_id).focus();
-};
-
 // http://stackoverflow.com/questions/4233265/contenteditable-set-caret-at-the-end-of-the-text-cross-browser
 exports.place_caret_at_end = function (el) {
     el.focus();