<img name=img1 src="arrow_l.gif" style="position:absolute;">
<script language=javascript>
var obj=document.getElementById("img1")
obj.style.left=Math.random()*1000;
obj.style.top=Math.random()*500;
</script>
<script language=javascript>
var obj=document.getElementById("img1")
obj.style.left=Math.random()*1000;
obj.style.top=Math.random()*500;
</script>
<img name="img1" src="http://community.csdn.net/images/csdn.gif" style="position:absolute;filter:alpha(opacity=0);">
</body>
<script language=javascript>
function fade(o){
this.obj = o;
this.offset=5;
this.timer = null;
this.act = "in";
this.action= function(){
//alert(this.obj.tagName);
var curOpacity = this.obj.filters.alpha.opacity;
if( this.act == "out" )
{
if(curOpacity > 0)
{
this.obj.filters.alpha.opacity-=this.offset;
}
else
{
this.act = "in";
this.obj.style.left= Math.random()*800 + "px";
this.obj.style.top = Math.random()*600 + "px";
}
}
else
{
if(curOpacity<100)
{
this.obj.filters.alpha.opacity+=this.offset;
}
else
{
this.act = "out";
}
}
};
this.play = function(){
var self=this;
var f = function(){self.action()};
this.timer=setInterval(f,40);
};
this.stop = function(){
if(this.timer) clearInterval( this.timer );
};
}
var m1 = document.images[0];
var f1 = new fade(m1);
f1.play();
</script>
this.offset=5;
this.timer = null;
this.act = "in";
这些变量中的this是什么啊?不需要用var来声明吗?我对它的用法不怎么清楚哈,麻烦你给详细说说啊???
按照你的要求最基本的代码就是下面这些，不过ice_berg16(寻梦的稻草人)的要好很多
<img name=img1 src="haha.gif" style="position:absolute;">
<script language=javascript>
function show()
{
var obj=document.getElementById("img1")
obj.style.left=Math.random()*1000;
obj.style.top=Math.random()*500;
setTimeout("show()",1000)
}
show()
</script>
this指定当前对象
当创建实例的时候
如f1 = new fade(m1);
这时候this指为f1
我想问问:
this.play = function(){
var self=this;
var f = function(){self.action()};
this.timer=setInterval(f,40);
在这段程序里,如果我把var f = function(){self.action()};中的self.action改成this.action
为什么就不行了呢?