fixed bug: multiple select always close when the options is clicked

Author: ibnujakaria

dist/js/app.js

@@ -1,6 +1,6 @@
 {
   "name": "multiple-select-js",
-  "version": "1.2.3",
+  "version": "1.2.4",
   "description": "Simple js library for html5 multiple select",
   "main": "src/MultipleSelect.js",
   "scripts": {

dist/js/app.js.gz

@@ -67,7 +67,7 @@ class MultipleSelect {
       selectedItems.push({ value: option.value, label: option.innerText })
     })
 
-    let isMultiple = select.getAttribute('multiple') !== null
+    let isMultiple = select.multiple
 
     select.insertAdjacentElement('afterend', root)
     select.hidden = true