SOURCE

$(document).ready(function() {
  $(".shoot").on("click", startDanmu);
  $(".clear").on("click", clearDanmu);
});

//get random number in certain range
function RandomNum(Min, Max) {
  var Range = Max - Min;
  var Rand = Math.random();
  var num = Min + Math.round(Rand * Range);
  return num;
}

//time number add 0 before if <10
function plusZero(x) {
  if (x < 10) {
    x = "0" + x;
  } else {
    x = x;
  }
  return x;
}

//start danmu
function startDanmu() {

  var message = $("input");
  var danmuMessage = "<span class='danmu-message'>" + message.val() + "</span>";

  //get random color HEX
  //u can also save the colors u want by array
  var color = RandomNum(100000, 999999);

  //get random danmu speed
  var speed = RandomNum(10000, 20000);

  //get random position Y
  //danmu box height is 450, we set the danmu position Y max 400 in case it blocks the subtitle
  var positionY = RandomNum(50, 400);

  //insert danmu message into danmu box
  $(".danmu-box").prepend(danmuMessage);

  //have to use first() cuz we prepend the message, u can try what's gonna happen if no first()
  //set it's style
  $(".danmu-message").first().css({
    "right": "0",
    "top": positionY,
    "color": "#" + color
  });

  //set it's animation
  //from right 0 to left 0
  //hide it after move
  $(".danmu-message").first().animate({
    left: '0px',
  },
  speed,
  function() {
    $(this).fadeOut();
  });

  //get danmu time
  var time = new Date();
  var month = time.getMonth() + 1;
  var day = time.getDay();
  var hour = time.getHours();
  var minute = time.getMinutes();
  var danmuTime = plusZero(month) + "-" + plusZero(day) + " " + plusZero(hour) + ":" + plusZero(minute);

  //insert danmu message to table
  var messageToTable = "<tr><td>" + message.val() + "</td><td>" + danmuTime + "</td></tr>";
  $(".danmu-table > tbody").prepend(messageToTable);

  //empty the input
  message.val("");
}

//clear danmu box
function clearDanmu() {
  $(".danmu-box").html("");
}

<div class="frame">
  <div class="row">
    <div class="col-xs-8 col-sm-8 col-md-8 col-lg-8 danmu-box-frame">
      <div class="danmu-box">
      </div>
    </div>
    <div class="col-xs-4 col-sm-4 col-md-4 col-lg-4 danmu-table-frame">
      <table class="table .table-condensed danmu-table">
        <thead>
          <tr>
            <th>
              弹幕内容
            </th>
            <th>
              弹幕时间
            </th>
          </tr>
        </thead>
        <tbody>
        </tbody>
      </table>
    </div>
  </div>
  <div class="danmu-form">
    <form class="form-inline">
      <input type="text" class="form-control" placeholder="开始吐槽！">
      <button type="button" class="btn btn-primary shoot">
        发射弹幕！
      </button>
      <button type="button" class="btn btn-danger clear">
        清空弹幕
      </button>
    </form>
  </div>
</div>
<hr>
<footer>
  Designed By
  <a href="http://blog.csdn.net/alenhhy" target="_blank">
    Alen Hu
  </a>
</footer>

* {
  font-family: '微软雅黑', sans-serif;
}

body {
  background: #f5f5f5;
}

.frame {
  width: 900px;
  margin: 0 auto;
}

.danmu-box {
  position: relative;
  overflow: hidden;
  width: 100%;
  height: 450px;
  margin: 30px 0 20px;
  background: white;
}

.danmu-message {
  position: absolute;
  display: inline-block;
}

.danmu-table-frame {
  overflow: auto;
  height: 450px;
  margin: 30px 0 20px;
  background: white;
}

.danmu-table {
  color: #aaa;
}

.danmu-table > thead > tr > th {
  font-weight: normal !important;
}

.danmu-form form {
  width: 60%;
  margin: 0 auto;
}

input {
  width: 60% !important;
}

button {
  width: 19%;
  background: #00a1d6;
}

hr {
  width: 60%;
  margin: 20px auto;
}

footer {
  font-size: 14px;
  text-align: center;
}

footer > a {
  text-decoration: none;
}

footer > a:hover,
footer > a:active,
footer > a:focus {
  text-decoration: underline;
}