JSFiddle - React, Tailwind, and code Playground

HTML

<select id="productchoice">
   <option value="1">Option #1</option>
   <option value="2">Option #2</option>
  </select>

  <select id="productchoice2">
   <option value="1">Option #1</option>
   <option value="2">Option #2</option>
  </select>
  
  <form name="main" id="main">
    Please input search parameters:
    <br/><input id="startDate" type="date" name="startDate">
    <br/><input id="endDate" type="date" name="endDate">
    <br/>
    <select id="timePeriod" name="timePeriod">
        <option value="none"> </option>
        <option value="lastQtr">Last Qtr</option>
        <option value="lastMonth">Last Month</option>
        <option value="lastCalendarYear">Last Calendar Year</option>
        <option value="currentYear">Current Year to Date</option>
        <option value="currentQtr">Current Qtr to Date</option>
        <option value="currentMonth">Current Month to Date</option>
    </select>
    <br/><input type="submit">
</form>

JavaScript

var period = document.getElementById("timePeriod");
var start = document.getElementById('startDate');
var end = document.getElementById('endDate');

var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yyyy = today.getFullYear();

//if(dd<10) {dd='0'+dd} 
//if(mm<10) {mm='0'+mm} 
//today = yyyy+'-'+mm+'-'+dd;

period.onchange = function(e){
		if (period.value == 'lastQtr') {
    		start.value = new Date(yyyy-5, mm, dd).toJSON().slice(0,10).replace(/-/g,'-');
        end.value = new Date().toJSON().slice(0,10).replace(/-/g,'-');
    }
    else if (period.value == 'lastMonth') {
    		
    }
    else if (period.value == 'lastCalendarYear') {
    		start.value = (yyyy-1)+'-'+'01'+'-'+'01';
        end.value = (yyyy-1)+'-'+12+'-'+31;
    }
    else if (period.value == 'currentYear') {
    		
    }
    else if (period.value == 'currentQtr') {
    		
    		start.value = yyyy+'-'+mm+'-'+'01';
        end.value = today;
    }
    else if (period.value == 'currentMonth') {
    		start.value = yyyy+'-'+mm+'-'+'01';
        end.value = today;
    }
}