一、設計思路
這個留言板有兩個大的版塊，一個是留言板（主要是發佈留言的內容會在上面顯示），另一個是發佈留言（可以在這裏輸入你想要留言的內容等）。下圖是留言版做成的樣子：
主要用到input textarea button img div等；還用到了date對象的知識來獲取時間，innerHTML來修改span中的內容。之後就是使用DOM的知識來實現這些功能。
二、代碼
html
<body οnlοad="f3()">
<div class="title">
<h1>留言板</h1>
<span id="step">一共有（）樓</span>
</div>
<div id="contents">
<div class="box" id="box">
<div class="div01">1樓</div>
<div class="tit"><img src="img/i1.png"></div>
<div class="main">
<div>姓名：</div>
<div>內容：</div>
</div>
<div class="div02">
<div><a href="javascript:void (0)" οnclick="del(this)">刪除</a>|<a href="javascript:void (0)" οnclick="praise(this,0)">點贊（）</a> </div>
<div>發佈時間：</div>
</div>
</div>
</div>
<div class="title1">
<h1>發佈留言</h1>
<span></span>
</div>
<div class="message">
<div class="nav">
選擇頭像：
<div id="img">
<img src="img/i1.png">
<img src="img/i2.jpg">
<img src="img/i3.jpg">
</div>
<div id="pic1"></div>
<div>用戶姓名：<input type="text" id="name" οnblur="f1(this)" οnfοcus="f(this,'請輸入用戶名!')"><span></span></div>
<div>留言內容：<textarea id="textarea" οnblur="f1(this)" οnfοcus="f(this,'請輸入內容！')"></textarea><span></span></div>
<button οnclick="f2()">發佈留言</button>
</div>
</div>
</body>
css
*{padding: 0;margin: 0;border: 0;text-decoration: none;}
.title{width: 1000px;height: 80px;background: #2b669a;margin: auto; color: #ffffff;}
.title h1{line-height: 80px;text-align: center;width: 920px;float: left;}
.title span{float: left;width: 80px;line-height: 80px;font-size: 12px;}
#contents{ width: 1000px;background:#9acfea;margin: auto;}
#contents .box{display:none;height: 150px;border-bottom: 1px dashed #ffffff;}
#contents .box .div01{width: 50px;text-align: center;float: left;line-height: 150px;}
#contents .box .tit{width: 80px;height: 80px;float: left;margin: 30px;}
#contents .box .tit img{width: 80px;height: 80px;}
#contents .box .main{width: 100px;height: 100px;float: left;margin-top: 30px;line-height: 40px;}
#contents .box .div02{font-size: 12px;width: 240px;height: 100px;float: right;line-height: 40px;margin-top: 30px;}
.title1{width: 1000px;height: 80px;background: #2b669a;margin: auto;color: #ffffff;}
.title1 span{float: left;width: 80px;line-height: 80px;font-size: 12px;}
.title1 h1{line-height: 80px;text-align: center;width: 920px;float: left;}
.message{width: 1000px;margin: auto;line-height:30px;background:#9acfea;height: 220px;}
.message .nav{width: 400px;margin-left: 400px;}
#img img{width:50px;height: 50px;}
.border{border: 1px solid crimson;}
.red{color:red;}
.border{border: 1px solid red;}
js
function f(obj,text) {
obj.nextSibling.innerHTML=text;
obj.nextSibling.style.color="#000";
obj.nextSibling.style.fontSize=12+'px';
}
function f1(obj) {
obj.nextSibling.innerHTML=" ";
}
//發佈留言
var i = 0;
//i 爲 box 的 id
var j = 0;
//j是一共有多少個樓，刪除後的用它接收
var q =1;
function f2() {
var name = document.getElementById("name");
var main = document.getElementById("textarea");
var box = document.getElementById("box");
var contents = document.getElementById("contents");
var step = document.getElementById("step");
var pic1 =document.getElementById("pic1");
if (name.value == "") {
name.nextSibling.innerHTML="*必須填寫用戶名!";
name.nextSibling.style.color="red";
name.nextSibling.style.fontSize=10+'px';
}else if(main.value == ""){
main.nextSibling.innerHTML="必須填寫內容";
main.nextSibling.style.color="red";
main.nextSibling.style.fontSize=10+'px';
}else if(q==1){
//選擇頭像
pic1.innerHTML="必須選中一個頭像！";
pic1.style.color="red";
pic1.style.fontSize=10+"px";
}else {
//樓層
var div = box.cloneNode(true);
div.style.display="block";
i++;
j++;
div.id="box"+i;
var child = div.getElementsByTagName("div");
//獲取克隆出來div裏面的小div
child[0].innerHTML=i+"樓";
child[3].innerHTML="姓名："+name.value;
child[4].innerHTML="內容："+main.value;
step.innerHTML="一共有（"+ j +"）樓";
child[7].innerHTML="發佈時間"+oTime();
contents.appendChild(div);
}
}
//發佈時間的時間
function oTime() {
var date = new Date();
var year = date.getFullYear();
var month = date.getMonth()+1;
var date1 = date.getDate();
var day = date.getDay();
var hour = date.getHours();
var minutes = date.getMinutes();
var second = date.getSeconds();
if(day === 0){
day = "日";
}else if(day == 1){
day = "一";
}else if(day == 2){
day = "二";
}else if(day == 3){
day = "三";
}else if(day == 4){
day = "四";
}else if(day == 5){
day = "五";
}else if(day == 6){
day = "六";
}
return year+"年"+month+"月"+date1+"日"+hour+"："+minutes+"："+second+"星期"+day;
}
//刪除
function del(obj) {
var step = document.getElementById("step");
j--;
step.innerHTML="一共有（"+ j +"）樓";
//刪除後一共有多少樓
var contents = document.getElementById("contents");
var p =obj.parentNode.parentNode.parentNode;
//removeChild(p)表示把p刪掉
contents.removeChild(p);
}
//點贊
function praise(obj,t) {
t++;
var parent1 = obj.parentNode;
parent1.innerHTML='<a href="javascript:void (0)" οnclick="del(this)">刪除</a>|' +
'<a href="javascript:void (0)" οnclick="praise(this,'+ t +')">點贊（'+ t +'）</a>';
}
//選擇頭像
function f3() {
var img = document.getElementById("img");
var pic = img.getElementsByTagName("img");
var box = document.getElementById("box");
var img1= box.getElementsByTagName("img");
for(var a =0; a<pic.length;a++){
pic[a].onclick=function () {
for(var b=0;b<pic.length;b++){
pic[b].className="";
}
this.className="border";
img1[0].src = this.src;
q=2;
pic1.innerHTML="";
}
}
}