JSFiddle - React, Tailwind, and code Playground

by Lokesh Yadav

HTML

<select name="ddlCategories0" onchange="javascript:setTimeout(&#39;__doPostBack(\&#39;ddlCategories0\&#39;,\&#39;\&#39;)&#39;, 0)" id="ddlCategories0" class="input Width250" onclick="Clear()">
<option value="0"> --SELECT--</option>
<option selected="selected" value="2">One</option>
<option value="3">Two</option>
</select>

 <select name="ddlCategories1" onchange="javascript:setTimeout(&#39;__doPostBack(\&#39;ddlCategories1\&#39;,\&#39;\&#39;)&#39;, 0)" id="ddlCategories1" class="input Width250" onclick="Clear()">
<option value="0"> --SELECT--</option>
<option value="2">One</option>
<option selected="selected" value="3">Two</option>
</select>

<span id="message"></span>

JavaScript

function Validate() {
    var spnMessage = document.getElementById('message');
        for (var i = 0; i < 2; i++) {
            var objCat = document.getElementById("ddlCategories" + i);
            if (objCat) { //check if objCat is not null or undefined but this has solved the issue.
                if (objCat.options[objCat.selectedIndex].text != "--SET--") {
                    for (var j = i; j < 6; j++) {
                        var objCatNext = document.getElementById("ddlCategories" + j);
                        if (objCat.options[objCat.selectedIndex].text == objCatNext.options[objCatNext.selectedIndex].text) {
                            spnMessage.innerHTML = objCatNext.options[objCatNext.selectedIndex].text + " exists.";
                            return false;
                       }
                    }
              }  }             
        }
        return true;
    }

Validate()