From 4624f6a51d4bf93e806e9ab09223989a2f6c032d Mon Sep 17 00:00:00 2001
From: Bartek Fabiszewski <github@fabiszewski.net>
Date: Thu, 12 Dec 2019 16:36:35 +0100
Subject: [PATCH] Throw error on wrong argument type

---
 js/src/select.js       | 3 +++
 js/test/select.test.js | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/js/src/select.js b/js/src/select.js
index a19479d..2eb6d6e 100644
--- a/js/src/select.js
+++ b/js/src/select.js
@@ -25,6 +25,9 @@ export default class uSelect {
    * @param {string=} all Optional all option text
    */
   constructor(element, head, all) {
+    if (!(element instanceof HTMLSelectElement)) {
+      throw new Error('Invalid argument for select');
+    }
     this.element = element;
     this.hasAllOption = false;
     this.allText = '';
diff --git a/js/test/select.test.js b/js/test/select.test.js
index b15a729..1eaef56 100644
--- a/js/test/select.test.js
+++ b/js/test/select.test.js
@@ -57,6 +57,12 @@ describe('Select tests', () => {
     expect(select.headText).toBe('');
   });
 
+  it('should should throw error on wrong obligatory parameter type', () => {
+    // when
+    // then
+    expect(() => new uSelect(null)).toThrowError(/Invalid argument/);
+  });
+
   it('should construct class instance with header', () => {
     // when
     const select = new uSelect(element, head);