选择输入onChange事件在Firefox浏览器中不能用于php响应式网站

my code are:-

  <select name="Priore" id="prioe" onchange="return showcolor()">
        <option> </option>
        <option value = "1">Red</option>
        <option value = "2">Blue</option>
  </select>

Show color function:-

  function showcolor()

    {

     alert('test');

    }

But, onchange event not working, Alert event not fire in Firefox browser. In chrome browser working proper.

In Firefox showcolor() function not working for iphone 6/7/8+ display.

How to Solved that issue?

Issue Solved,

Any Website opened in iPhone Firefox browser any drop-down not open, it's actually not a issue(drop-down in working condition).

Testing drop-down in mobile iPhone then drop-down work properly.