If you want to ask a question from users, avoid classic JavaScript confirm box. Instead use a beautiful popup modal. The code here will shows a popup when a button is clicked. The popup contains accept and cancel buttons with a cross shaped close button for closing the window. You should code your desired actions for when the modal is accepted or cancelled.

HTML
<!-- this script got from www.devanswer.com -->
<div class="flex"> <div class="modalcontainer"> <div class="flex"> <div class="modal"> <div class="close"><span>+</span></div> <div class="content"> <h2>Modal title</h2> <p>Let's go up in here, and start having some fun The very fact that you're aware of suffering is enough reason to be overjoyed that you're alive and can experience it. It's a super day, so why not make a beautiful sky?</p> </div> <div class="buttons"> <a href="#0">Cancel</a> <a href="#0">Accept</a> </div> </div> </div> </div> <a href="#0" class="modalbttn">Open Modal</a> </div> <script src='https://code.jquery.com/jquery-2.2.4.min.js'></script><a style="font-size: 8pt; text-decoration: none" target="_blank" href="http://www.devanswer.com">Developer Code</a>

CSS
@import "https://fonts.googleapis.com/css?family=Source+Sans+Pro:400,600";
*,
*::before,
*::after {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}

html, body {
  height: 100%;
  width: 100%;
}

a {
  color: #FFF;
  text-decoration: none;
}
a:hover {
  text-decoration: none;
}

body {
  padding: 0px;
  margin: 0;
  font-family: "Source Sans Pro", sans-serif;
  background: #644cad;
  background: -moz-linear-gradient(left, #644cad 0%, #4426a8 100%);
  background: -webkit-linear-gradient(left, #644cad 0%, #4426a8 100%);
  background: linear-gradient(to right, #644cad 0%, #4426a8 100%);
  -webkit-font-smoothing: antialiased;
}

h2 {
  margin-top: 0px;
  color: #4d5c6e;
  font-weight: 400;
}

p {
  color: #72879e;
  font-size: 16px;
  line-height: 24px;
}

.blur {
  -webkit-filter: blur(5px);
  -moz-filter: blur(5px);
  -o-filter: blur(5px);
  -ms-filter: blur(5px);
  filter: blur(5px);
}

.flex {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
}

.modalcontainer {
  display: none;
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: rgba(0, 0, 0, 0.5);
}
.modalcontainer.active {
  display: block;
}

.modal {
  display: none;
  position: relative;
  width: 600px;
  height: 330px;
  background-color: #FFF;
}
.modal.active {
  display: block;
}
.modal .content {
  padding: 30px;
}
.modal .close {
  font-family: "Source Sans Pro", sans-serif;
  cursor: pointer;
  color: #FFF;
  width: 50px;
  height: 50px;
  text-align: center;
  line-height: 50px;
  position: absolute;
  right: 0;
  color: #999;
  font-size: 40px;
}
.modal .close span {
  transform: rotate(45deg);
  display: block;
}
.modal .buttons {
  width: 600px;
  position: absolute;
  bottom: 0;
  height: 50px;
  background-color: #FFF;
}
.modal .buttons a {
  width: 50%;
  height: 50px;
  line-height: 50px;
  text-align: center;
  float: left;
  background-color: #EEE;
  color: #4d5c6e;
  transition: 0.3s;
  text-transform: uppercase;
  font-weight: bold;
}
.modal .buttons a:hover {
  background-color: #e1e1e1;
}
.modal .buttons a:nth-of-type(2) {
  float: right;
  color: #FFF;
  background-color: #00c06d;
}
.modal .buttons a:nth-of-type(2):hover {
  background-color: #00a75f;
}

.modalbttn {
  background-color: #24252A;
  padding: 12px 25px;
  text-transform: uppercase;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
  border-bottom: 1px solid rgba(0, 0, 0, 0.2);
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23);
  border-radius: 4px;
}
.modalbttn:hover {
  background-color: #2b2c32;
}
Javascript
$(".modalbttn").click(function () {
  $(".modalcontainer").fadeIn("slow");
  $(".modal").fadeIn("slow");
});

$(".close").click(function () {
  $(".modalcontainer").fadeOut("slow");
  $(".modal").fadeOut("slow");
});

$(".buttons").click(function () {
  $(".modalcontainer").fadeOut("slow");
  $(".modal").fadeOut("slow");
});