javascript元素内容渐现效果代码实例
分类：实例代码
本章节分享一段代码实例，他实现了元素的渐现效果。
代码实例如下:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.pipipi.net/" />
<title>前端教程网</title>
<style>
*{
margin:5px;
}
body, ul, li{
margin:0;
padding:0;
font:12px/1.5 arial;
}
#list{
width:400px;
}
#list li{
list-style:none;
padding:5px 0;
overflow:hidden;
border-bottom:1px dotted #ccc;
filter:alpha(opacity:0);
opacity:0;
vertical-align: middle;
}
</style>
<script>
window.onload = function(){
var btn = document.getElementById("btn");
var con = document.getElementById("con");
var list = document.getElementById("list");
var list_li = list.getElementsByTagName("li");
btn.onclick = function(){
var li = document.createElement("li");
li.innerHTML = con.value;
con.value='';
if(list_li.length>=1){
list.insertBefore(li,list_li[0]);
}
else{
list.appendChild(li);
}
var height=li.offsetHeight;
li.style.height='0';
startrun(li,"height",height,function(){
startrun(li,"opacity","100");
})
}
}
function getstyle(obj,name){
if(obj.currentStyle){
return obj.currentStyle[name];
}
else{
return getComputedStyle(obj,false)[name];
}
}
function startrun(obj,attr,target,fn){
clearInterval(obj.timer);
obj.timer = setInterval(function(){
var cur = 0;
if(attr == "opacity"){
cur = Math.round(parseFloat(getstyle(obj,attr))*100);
}
else{
cur = parseInt(getstyle(obj,attr));
}
var speed = (target-cur)/8;
speed = speed>0?Math.ceil(speed):Math.floor(speed);
if(cur == target){
clearInterval(obj.timer);
if(fn){
fn();
}
}
else{
if(attr == "opacity"){
obj.style.filter = "alpha(opacity="+(cur+speed)+")";
obj.style.opacity = (cur+speed)/100;
}
else{
obj.style = cur + speed + "px";
}
}
},30)
}
</script>
</head>
<body>
<textarea id="con" cols="50" rows="5"></textarea>
<input id="btn" name="" type="button" value="发布">
<ul id="list"></ul>
</body>
</html>
在多行文本框输入内容，然后点击按钮之后，就可以看到文档内容的渐现效果。