react-widgets: Add combobox placeholder (#16288)

* react-widgets: add combobox placeholder

* Add name to definitions by

types/react-widgets/index.d.ts

@@ -1,6 +1,6 @@
 // Type definitions for react-widgets 3.2
 // Project: https://github.com/jquense/react-widgets
-// Definitions by: Rogier Schouten <https://github.com/rogierschouten/>, Balázs Sándor <https://github.com/sanyatuning>
+// Definitions by: Rogier Schouten <https://github.com/rogierschouten/>, Balázs Sándor <https://github.com/sanyatuning>, Frode Hansen <https://github.com/frodehansen2>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 2.1
 

types/react-widgets/lib/Combobox.d.ts

@@ -73,6 +73,11 @@ interface ComboBoxProps extends ReactWidgetsCommonDropdownProps<ComboBoxClass> {
      * the groupBy value will be used.
      */
     groupComponent?: React.ReactType;
+    /**
+     * The same as an input placeholder, only works in browsers that support the placeholder
+     * attribute for inputs
+     */
+    placeholder?: string;
     /**
      * When true the Combobox will suggest, or fill in, values as you type. The suggestions are
      * always "startsWith", meaning it will search from the start of the textField property

types/react-widgets/react-widgets-tests.tsx

@@ -47,7 +47,7 @@ class Test extends React.Component<React.Props<{}>, {}> {
             </div>
             <div>
                 <Calendar disabled readOnly />
-                <Combobox disabled readOnly dropUp />
+                <Combobox disabled readOnly dropUp placeholder={'Some text'}/>
                 <DateTimePicker disabled readOnly dropUp />
                 <DropdownList disabled readOnly dropUp />
                 <Multiselect disabled readOnly dropUp />