JSFiddle - React, Tailwind, and code Playground

HTML

<div id="firstdiv">	
		<div name = "div_1a">
	 			  1.เลืือกคำถามที่ต้องการไป
					<select id="select_1a" name="select_1a" >
						<option checked ></option>
						<option value="1">1</option>
						<option value="2">2</option>
						<option value="3">3</option>
						<option value="4">4</option>
					</select>
				</div>
				<br>
<div name= "div_1b">
					<p>1b. Q1b?</p>
				    	<input type="radio" name="1bradiogroup" value="1"> 1 <br>
				    	<input type="radio" name="1bradiogroup" value="2"> 2 <br>
				    	<input type="radio" name="1bradiogroup" value="3"> 3 <br>
		
			    </div>
						<input type='button' id = "q1Next_btn" value='Save and Continue' />
 		 	</div>	

 		 	<div id="secdiv" style="display:none">		
	 		 		<h1>2. Q2a</h1>				
	 				<br>
	 			<div id="div_2a" name = "div_2a">
				2a.	just hit back btn to go back to Q1
                    <select id="select_2a" name="select_2a">
						<option ></option>
						<option value="1">1</option>
						<option value="2">2</option>
						<option value="3">3</option>	
					</select>
				</div>
				<div id="div_2b" name= "div_2b">
					<p>2b. Q2b?</p>
				    	<input type="radio" name="2bradiogroup" value="1"> No <br>
				    	<input type="radio" name="2bradiogroup" value="2"> Yes <br>
				    	
			    </div>
						<input type='button' id="q2Back_btn" value='Back'  />
						<input type='button' id="q2Next_btn" value='Save and Continue'/>
 		 	</div>

JavaScript

$("#q1Next_btn").click(function(){ 
    		//put Q1 logic here..
	    if($("#select_1a option:selected").val()==1){
	    	$("#firstdiv").hide(500);
	    	$("#secdiv").show(500);
	   
	    }else if($("#select_1a option:selected").val()==2){

			$("#firstdiv").hide(500);
	    	$("#secdiv").show(500);
	    	// $("#select_2a").attr("disabled",true);
	    }     
        
    });
    // --Q1 question handler END--
    // --Q2 question handler--
     $("#q2Back_btn").click(function(){ 
    		//put Q2 logic here..
                $('#select_2a').prop('selectedIndex',0); 
                $('#div_2b').find("input[type='checkbox'],input[type='radio']").prop('checked',false);
                $("#secdiv").hide(500);
	    	$("#firstdiv").show(500);
});