Merge pull request #7 from piotr-gawron/create-from-dom-object

Create from dom object

src/dual-listbox.js

@@ -19,11 +19,15 @@ const SELECTED_MODIFIER = 'dual-listbox__item--selected';
 class DualListbox {
     constructor(selector, options={}) {
         this.setDefaults();
-        this.select = document.querySelector(selector);
-
         this.selected = [];
         this.available = [];
 
+        if (this.isDomElement(selector)) {
+            this.select = selector;
+        } else {
+            this.select = document.querySelector(selector);
+        }
+
         this._initOptions(options);
         this._initReusableElements();
         this._splitSelectOptions(this.select);
@@ -439,6 +443,17 @@ class DualListbox {
             }
         }
     }
+
+    /**
+     * @Private
+     * Returns true if argument is a DOM element
+     */
+    isDomElement(o) {
+        return (
+            typeof HTMLElement === "object" ? o instanceof HTMLElement : //DOM2
+                o && typeof o === "object" && o !== null && o.nodeType === 1 && typeof o.nodeName === "string"
+        );
+    }
 }
 
 export default DualListbox;

test/dual-listbox.spec.js

@@ -289,4 +289,13 @@ describe('Duallistbox', function() {
         expect(dlb.available.length).toBe(10);
         expect(dlb.selected.length).toBe(0);
     });
+
+    it('should be able to create object from DOM element', () => {
+        let domParent = document.createElement("div");
+        domParent.innerHTML = FIXTURE_FILLED_SELECT;
+        let dlb = new DualListbox(domParent.getElementsByTagName('select')[0]);
+
+        expect(dlb.available.length).toBe(10);
+        expect(dlb.selected.length).toBe(0);
+    });
 });