Javascript issue – pure code without using cdn or javascript library like jquery

I have code that was working with Jquery however I have been asked to convert to pure Javascript as there a preference for using JS only.

I have tried without success and also tried to use an online converter but this didn’t work great and was still giving errors.

Just wondering if someone could take a look at the jquery code that was working for suggestions on how to get the same working with Javascript only.

$('.one').click(function() {
  $(this).toggleClass('selected');
  $('.two').removeClass('selected');
});

$('.two').click(function() {
  $(this).toggleClass('selected');
  $('.one').removeClass('selected');
});

$('.ready').click(function() {
  if ($(".one").hasClass("selected")) {
    $("#sec-1").hide();
    $("#sec-2").show();
  } else if ($(".two").hasClass("selected")) {
    $("#sec-1").show();
    $("#sec-2").hide();
  }
});

$('.return').click(function() {
  $("#sec-1").show();
  $("#sec-2").hide();
  $("#grid").empty();
});

obj = JSON.parse(json - data - 1);
obj1 = JSON.parse(json - data - 2);

//create objects
function Product(image, title, link) {
  this.image = image;
  this.title = title;
  this.link = link;
}

// Create Product Objects
var used = false;

$('.btn-test').click(function(e) {
  if (used == false) {
    used = true;
    e.preventDefault();
    $("#grid").append("<br/><p class='hello'>Hello " + $('#txt_name').val() + " , <br/><br/> here's the output </p>");
    if ($(".testclass").hasClass("selected")) {
      for (var i = 0; i < obj.Products.length; i++) {
        new Product("obj.Products[i].image", "obj.Products[i].title", "obj.Products[i].link");
        $("#grid").append("<div class='grid-item'><div><img src='" + obj.Products[i].image + "</p> </div><div>" + obj.Products[i].price + "</div><div class='prod'> <a class='product' href='" + obj.Products[i].link + "'>Go to Product Page" + "</a></div></div>");
      }
      $("#grid").append("<br/><p class='grid-link'><a href=" + '' + ">Go to</a></p>");
    } else if ($(".testclass1").hasClass("selected")) {
      for (var i = 0; i < obj1.Products.length; i++) {
        new Product("obj1.Products[i].image", "obj1.Products[i].title", "obj1.Products[i].link");
        $("#grid").append("<div class='grid-item'><div><img src='" + obj1.Products[i].image + "</p> </div><div>" + obj1.Products[i].price + "</div><div class='prod'> <a class='product' href='" + obj1.Products[i].link + "'>Go to Product Page" + "</a></div></div>");
      }
      $("#grid").append("<br/><p class='grid-link'><a href=" + '' + ">Go to</a></p>");
    }
  }
  used = false;
});