perf(ngOptions): prevent initial options repainting

pbr1111 · Narretz · commit ff52b188a759 · 2017-06-29T10:54:53.000+02:00
Avoid double execution of `updateOptions()` method, which causes a complete repainting of all `<option>` elements. Fixes angular#15801 Closes angular#15812 Close angular#16071
diff --git a/src/ng/directive/ngOptions.js b/src/ng/directive/ngOptions.js
@@ -453,6 +453,9 @@ var ngOptionsDirective = ['$compile', '$document', '$parse', function($compile,
       if (!multiple) {
 
         selectCtrl.writeValue = function writeNgOptionsValue(value) {
+          // The options might not be defined yet when ngModel tries to render
+          if (!options) return;
+
           var selectedOption = selectElement[0].options[selectElement[0].selectedIndex];
           var option = options.getOptionFromViewValue(value);
 
@@ -504,9 +507,11 @@ var ngOptionsDirective = ['$compile', '$document', '$parse', function($compile,
       } else {
 
         selectCtrl.writeValue = function writeNgOptionsMultiple(values) {
+          // The options might not be defined yet when ngModel tries to render
+          if (!options) return;
+
           // Only set `<option>.selected` if necessary, in order to prevent some browsers from
           // scrolling to `<option>` elements that are outside the `<select>` element's viewport.
-
           var selectedOptions = values && values.map(getAndUpdateSelectedOption) || [];
 
           options.items.forEach(function(option) {
@@ -588,10 +593,6 @@ var ngOptionsDirective = ['$compile', '$document', '$parse', function($compile,
 
       }
 
-      // We need to do this here to ensure that the options object is defined
-      // when we first hit it in writeNgOptionsValue
-      updateOptions();
-
       // We will re-render the option elements if the option values or labels change
       scope.$watchCollection(ngOptions.getWatchables, updateOptions);
 
