Work around a selectize bug (re-fixes #3966)

NEWS.md

@@ -22,6 +22,8 @@
 
 * Fixed a bug with stack trace capturing that caused reactives with very long async promise chains (hundreds/thousands of steps) to become extremely slow. Chains this long are unlikely to be written by hand, but {coro} async generators and {elmer} async streaming were easily creating problematically long chains. (#4155)
 
+* Updating the choices of a `selectizeInput()` via `updateSelectizeInput()` with `server = TRUE` no longer retains the selected choice as a deselected option if the current value is not part of the new choices. (@dvg-p4 #4142)
+
 # shiny 1.9.1
 
 ## Bug fixes

inst/www/shared/shiny.js

@@ -10662,10 +10662,8 @@
         }
         if (hasDefinedProperty(data, "url")) {
           var _selectize2 = this._selectize(el);
+          _selectize2.clear();
           _selectize2.clearOptions();
-          if (hasDefinedProperty(data, "value")) {
-            _selectize2.clear();
-          }
           var loaded = false;
           _selectize2.settings.load = function(query, callback) {
             var settings = _selectize2.settings;

srcts/src/bindings/input/selectInput.ts

@@ -142,13 +142,13 @@ class SelectInputBinding extends InputBinding {
         };
       };
 
+      // Calling selectize.clear() first works around https://github.com/selectize/selectize.js/issues/2146
+      // As of selectize.js >= v0.13.1, .clearOptions() clears the selection,
+      // but does NOT remove the previously-selected options. So unless we call
+      // .clear() first, the current selection(s) will remain as (deselected)
+      // options. See #3966 #4142
+      selectize.clear();
       selectize.clearOptions();
-      // If a new `selected` value is provided, also clear the current selection (otherwise it gets added as an option).
-      // Note: although the selectize docs suggest otherwise, as of selectize.js >v0.15.2,
-      // .clearOptions() no longer implicitly .clear()s (see #3967)
-      if (hasDefinedProperty(data, "value")) {
-        selectize.clear();
-      }
       let loaded = false;
 
       selectize.settings.load = function (query: string, callback: CallbackFn) {