Allow setting a placeholder from data attribute

Use data-placeholder="" on the select

fixes danielfarrell#12

Author: Daniel Farrell

js/bootstrap-combobox.js

@@ -30,7 +30,7 @@
     this.sorter = this.options.sorter || this.sorter
     this.highlighter = this.options.highlighter || this.highlighter
     this.$menu = $(this.options.menu).appendTo('body')
-    this.placeholder = this.options.placeholder || this.placeholder
+    this.placeholder = this.options.placeholder || this.$target.attr('data-placeholder')
     this.$element.attr('placeholder', this.placeholder)
     this.shown = false
     this.refresh()

js/tests/unit/bootstrap-combobox.js

@@ -220,4 +220,12 @@ $(function () {
 
         equals($input.attr('placeholder'), 'Type something...', 'input value was correctly set')
       })
+
+      test("should set placeholder text on the input if specified as an data attribute", function() {
+        var $select = $('<select data-placeholder="Type something..."><option></option><option>aa</option><option selected>ab</option><option>ac</option></select>')
+          , $input = $select.combobox().data('combobox').$element
+          , combobox = $select.data('combobox')
+
+        equals($input.attr('placeholder'), 'Type something...', 'input value was correctly set')
+      })
 })