JSFiddle - React, Tailwind, and code Playground

HTML

Date:<input id="date" type="date" name="task_date" />
Time:<input id="time" type="time" name="task_time" />
<button id="calc">Get Time</button>

JavaScript

var calc = document.getElementById("calc")

calc.addEventListener("click", function() {
    var date = document.getElementById("date").value,
        time = document.getElementById("time").value
    
    console.log(new Date(date + " " + time))
})