模拟消息对话框完整版

CSS:

ul,li{list-style: none;padding: 0;margin: 0;}
    .cont{
        width: 527px;
        height: 600px;
        margin:30px auto;
        overflow: hidden;
        border: 1px solid #ccc;
    }
    #div1{
        width:527px;
        height: 499px; 
        border-bottom: 1px solid #ccc;
        position: relative;
        overflow-y:scroll;/* 显示纵向滚动条 */
    }
    #ul1>li{
        margin:10px 0;
        position: relative;
        height: auto;
        width: 510px;
        min-height: 50px;
    }
    #ul1>li:after{
        content: '.';
        display: block;
        height: 0;
        clear: both;
        visibility: hidden;
    }
    .bottom{
        width: 510px;
        height: 100px;
        background: #eee;
        overflow: hidden;
        position: relative;
    }
    .pic1{
        width: 80px;
        height: 80px;
        float: left;
        margin: 10px;
        border-radius:40px;
        /* overflow: hidden; */
        background-image: url(http://h.hiphotos.baidu.com/image/pic/item/7c1ed21b0ef41bd54a40316353da81cb39db3d12.jpg);
        background-position: 0 0;
    }
    .pic2{
        width: 80px;
        height: 80px;
        float: left;
        margin: 10px;
        border-radius:40px;
        /* overflow: hidden; */
        background-image: url(http://h.hiphotos.baidu.com/image/pic/item/7c1ed21b0ef41bd54a40316353da81cb39db3d12.jpg);
        background-position: -200px -200px;
    }
    .fl{float: left;}
    .text1{
        width: 300px;
        height:36px;
        margin: 30px 0px;
        border: 1px solid #ccc;
        overflow: hidden;
    }
    .btn2{
        width: 80px;
        height: 40px;
        line-height: 40px;
        text-align: center;
        margin: 30px 12px;
        border: 1px solid #ccc;
        background: #fff;
        font-size: 18px;
        overflow: hidden;
    }
/* 消息发送出后，消息框的消息内容和头像的样式 */
    #ul1 .pic1{
        width: 100px;
        height: 100px;
        /* position: absolute;
        left: 5px;
        display: inline; */
        border-radius: 50px;
        float: left;
    }
    #ul1 .pic2{
        width: 100px;
        height: 100px;
        /* position: absolute;
        right: 5px;
        display: inline; */
        border-radius: 50px;
        float: right;
    }
    /* #div1 li:last-child{
        max- 310px;
        padding: 20px;
        border-radius: 15px;
        line-height: 25px;
        position: absolute;
    } */
    #ul1 span{
        display: block;
        /* float: left; */
        max-width: 300px;
        height: auto;
        padding: 20px;
        margin-top:20px;
        /* margin-left: 20px; */
        border-radius: 15px;
        box-shadow: 0 5px 25px #ccc;
        line-height: 25px;
        word-wrap:break-word;/* 字母换行 */
    }
    #ul1 .msg1{
        float: left;
        margin-left: 15px;
        /* box-shadow: 0 5px 25px #ccc; */
    }
    #ul1 .msg1:before/* ,#ul1 span:before */{
        content: '';
        border:10px solid transparent;
        border-right-color: #ccc;
        position: absolute;
        left: 115px;
        top: 40px; 
    }
    #ul1 .msg2{
        float: right;
        margin-right: 15px;
    }
    #ul1 .msg2:after{
        content: '';
        border:10px solid transparent;
        border-left-color: #ccc;
        position: absolute;
        right: 115px;
        top: 40px;
    }

HTML:

<div class="cont">
    <div id="div1">
        <ul id="ul1"></ul>
    </div>
    <div class="bottom">
        <div id="btn1">
            <div class="pic1"></div>
        </div>
        <input id="text1" class="fl text1" type="text">
        <input id="btn2" class="fl btn2" type="button" value="发送">
    </div>
</div>

JS:

<script type="text/javascript">
    var oUl=document.getElementById('ul1');
    var oBtn1=document.getElementById('btn1');
    var oBtn2=document.getElementById('btn2');
    var oText1=document.getElementById('text1');
    var oImg=oBtn1.getElementsByTagName('div')[0];
    var onOff=true;//设置切换开关

    //头像切换
    oBtn1.onclick=function(){
        if (onOff) {
            oImg.className='pic2';//点击btn1时，切换图片，切换开关
            onOff=false;
        }
        else{
            oImg.className='pic1';
            onOff=true;
        };
    }

    function Tab(){
        if (oText1.value=='') {
            alert('请输入内容！');
        }else{
            oUl.innerHTML=('<li>'+oBtn1.innerHTML+'<span>'+oText1.value+'</span>'+'</li>' )+oUl.innerHTML;
            
            for (var i = 0; i < aLi.length; i++) {
                fnEnd(aLi[i]);//调用给li添加样式的函数
            };

            oText1.value='';//清空输入框的内容
            //alert(1);测试
        };
    }

    //点击发送时
    oBtn2.onclick=function(){
        Tab();
    }

    //给li下的span元素添加样式
    var aLi=oUl.getElementsByTagName('li');
    function fnEnd(li){
        var aDiv=li.getElementsByTagName('div')[0];
        var aSpan=li.getElementsByTagName('span')[0];
        if(aDiv.className=='pic1'){
            aSpan.className='msg1';//alert(1);
        }else{
            aSpan.className='msg2';
        };    
    }
    
    
    //键盘事件，按回车键发送消息
    oText1.onkeydown=function(ev){
        var oEvet=ev||event;//兼容性(火狐)
        //回车键的键值：13
        if (oEvet.keyCode==13) {
            Tab();
        };
    }

效果图：