原生javascript实现无间缝滚动示例_javascript技巧

// 写在匿名函数里面，防止全局变量污染
(function(){
var target = document.getElementById('marScroll'),
oUl = target.getElementsByTagName('ul')[0];
// 内容少，则直接退出此函数
if(oUl.offsetHeight})();

target.innerHTML += target.innerHTML;
/* 判断每次滚动的距离等于第一个ul的高度时，设置scrollTop为0，然后如此的循环操作就是无间滚动了
---------------------------------------------------------------------------------------------*/
// 把功能函数抽离出来，方便调用
var fn = function(){
if(target.scrollTop == oUl_h){
target.scrollTop = 0;
}else{
target.scrollTop++;
}
}
// setInterval 循环
var timer = setInterval(function(){
fn();
},30);

// hover
target.onmouseover = function(){
clearTimeout(timer);
}
target.onmouseout = function(){
timer = setInterval(function(){
fn();
},30);
}

// 写在匿名函数里面，防止全局变量污染
(function(){
var target = document.getElementById('marScroll'),
oUl = target.getElementsByTagName('ul')[0],
oUl_h = oUl.offsetHeight;
// 内容少，则直接退出此函数
if(oUl_h
target.innerHTML += target.innerHTML;

/* 判断每次滚动的距离等于第一个ul的高度时，设置scrollTop为0，然后如此的循环操作就是无间滚动了
---------------------------------------------------------------------------------------------*/
// 把功能函数抽离出来，方便调用
var fn = function(){
if(target.scrollTop == oUl_h){
target.scrollTop = 0;
}else{
target.scrollTop++;
}
}
// setInterval 循环
var timer = setInterval(function(){
fn();
},30);
// hover
target.onmouseover = function(){
clearTimeout(timer);
}
target.onmouseout = function(){
timer = setInterval(function(){
fn();
},30);
}
})();

function GyMarquee(opt){
this.opt = opt;
if(!document.getElementById(this.opt.targetID)) return;
this.target = document.getElementById(this.opt.targetID);
this.dir = this.opt.dir == 'crosswise'?'crosswise':'vertical';
this.effect = this.opt.effect == 'scroll'?'scroll':'marque';
this.scrollHeight = this.opt.scrollHeight;
this.init();
}
GyMarquee.prototype = {
marquee:function(){
var _that = this,
direction = 'scrollTop',
judge = this.target.scrollHeight,
timer = null;
if(this.dir == 'crosswise'){
direction = 'scrollLeft';
judge = this.itemLen*this.opt.itemWidth;
this.targetChild.style.width = this.itemLen*this.opt.itemWidth*2 + 'px';
}
var doFn = function(){
if(_that.target[direction] == judge){
_that.target[direction] = 0;
}
_that.target[direction]++;
}
timer = setInterval(function(){
doFn();
},38);
this.target.onmouseover = function(){
if(timer) clearTimeout(timer);
}
this.target.onmouseout = function(){
timer = setInterval(function(){
doFn();
},38);
}
},
scrollDo:function(){
var can = true,
_that = this;
this.target.onmouseover=function(){can=false};
this.target.onmouseout=function(){can=true};
new function (){
var stop=_that.target.scrollTop%_that.scrollHeight==0&&!can;
if(!stop)_that.target.scrollTop==parseInt(_that.target.scrollHeight/2)?_that.target.scrollTop=0:_that.target.scrollTop++;
setTimeout(arguments.callee,_that.target.scrollTop%_that.scrollHeight?20:2500);
};
},
getByClassName:function(className,parent){
var elem = [],
node = parent != undefined&&parent.nodeType==1?parent.getElementsByTagName('*'):document.getElementsByTagName('*'),
p = new RegExp("(^|\\s)"+className+"(\\s|$)");
for(var n=0,i=node.length;nif(p.test(node[n].className)){
elem.push(node[n]);
}
}
return elem;
},
init:function(){
var val = 0;
if(this.dir =='crosswise'&&this.effect=='marque'&&this.opt.itemName!=''){
this.itemLen = this.target.getElementsByTagName(this.opt.itemName).length;
val = this.itemLen*this.opt.itemWidth;
}else{
val = this.target.scrollHeight;
}
var holderHTML = this.target.innerHTML;
this.target.innerHTML = '

'+holderHTML+'

';
this.targetChild = this.getByClassName('J_scrollInner',this.target)[0];
var attr = this.dir == 'vertical'?'offsetHeight':'offsetWidth';
if(val>this.target[attr]){
if(this.effect == 'scroll'){
this.scrollDo();
}else{
this.marquee();
}
this.targetChild.innerHTML += this.targetChild.innerHTML;
}
}
}