JSFiddle - React, Tailwind, and code Playground

HTML

<form method="post" action="" id="myForm">
    <input name="true_ans[]" value="AC" />
    <input name="true_ans[]" value="AC" />
    <input name="true_ans[]" value="A" />
    <input name="true_ans[]" value="" />

    <select name="qtype[]">
     <option value="SINGLE">SINGLE</option> 
     <option value="MULTIPLE" selected>MULTIPLE</option>
     <option value="DESC">DESC</option>
    </select>
    
    <select name="qtype[]">
     <option value="SINGLE" selected>SINGLE</option> 
     <option value="MULTIPLE" >MULTIPLE</option>
     <option value="DESC">DESC</option>
    </select>

    <select name="qtype[]">
     <option value="SINGLE" selected>SINGLE</option> 
     <option value="MULTIPLE">MULTIPLE</option>
     <option value="DESC">DESC</option>
    </select>

    <select name="qtype[]">
     <option value="SINGLE">SINGLE</option> 
     <option value="MULTIPLE">MULTIPLE</option>
     <option value="DESC" selected>DESC</option>
    </select>

</form>

JavaScript

var true_ans_array = new Array();
$("input[name='true_ans[]']").each(function(){
    true_ans_array.push(this.value);
   
});

var qtype_array = new Array();
$('select[name="qtype[]"]').each(function(){
    qtype_array.push($(this).val());

});

for (i=0; i < qtype_array.length; i++) {

    switch (qtype_array[i]) {
    case "MULTIPLE": if (true_ans_array[i].length >= 2) 
                        {alert("it's >= than 2")} 
                     break; 
    case "SINGLE": if (true_ans_array[i].length == 1) 
                       {alert("it's == to 1")}
                   break; 
        case "DESC": if (true_ans_array[i].length == 0) 
                     {alert("it's == to 0")}
                  break; 
    default: alert("neither Multiple, Single or Desc");

    }
}