jQuery实现弹幕APP的实例分析

<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> 

$(document).ready(function() { 
 $(".shoot").on("click", startDanmu); 
 $("form").keypress(function(event) { 
 if (event.keyCode === 13) { 
  event.preventDefault(); 
  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 messageVal = message.val(); 
 var danmuMessage = "<span class='danmu-message'>" + messageVal + "</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); 
 
 if (messageVal.length > 0) { 
 //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 
 if (messageVal.length > 6) { 
  messageVal = messageVal.substring(0, 6) + "..."; 
 } 
 var messageToTable = "<tr><td>" + messageVal + "</td><td>" + danmuTime + "</td></tr>"; 
 $(".danmu-table > tbody").prepend(messageToTable); 
 
 } else {} 
 
 //empty the input 
 message.val(""); 
} 
 
//clear danmu box 
function clearDanmu() { 
 $(".danmu-box").html(""); 
}