Native javascript implements the seamless scrolling example

Vertical and horizontal scrolling are currently supported

http://lgyweb.com/marScroll/

Now analyze the basic idea of seamless seam realization (vertical example) :

HTML structure:

 
<div id="marScroll"> 
<ul> 
<li>01</li> 
<li>02</li> 
<li>03</li> 
<li>04</li> 
<li>05</li> 
</ul> 
</div> 

CSS:

 


<style type="text/css"> 
ul,li{padding: 0;margin: 0;} 
#marScroll{height: 60px;overflow: hidden;} 
#marScroll li{height: 20px;line-height: 20px;font-size: 14px;} 
</style> 

(1) first of all, it is necessary to determine whether the height of ul structure inside is higher than the outer layer of div#marScrolll before seamless scrolling:

 
//Write in anonymous functions to prevent global variable contamination
(function(){ 
var target = document.getElementById('marScroll'), 
oUl = target.getElementsByTagName('ul')[0]; 
//If there is little content, exit the function directly
if(oUl.offsetHeight<target.offsetHeight) return; 
})(); 

(2) seamless seam is the infinite scrolling display of contents, so the contents inside need to be copied first, and then through the scrollTop++ attribute of the outer layer, the setInterval function is used for loop execution

 
target.innerHTML += target.innerHTML; 
 
//Pull function function out, convenient call
var fn = function(){ 
if(target.scrollTop == oUl_h){ 
target.scrollTop = 0; 
}else{ 
target.scrollTop++; 
} 
} 
//SetInterval cycle
var timer = setInterval(function(){ 
fn(); 
},30); 

(3) stop scrolling when the mouse passes over the content block

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

Example JS total code:

 
//Write in anonymous functions to prevent global variable contamination
(function(){ 
var target = document.getElementById('marScroll'), 
oUl = target.getElementsByTagName('ul')[0], 
oUl_h = oUl.offsetHeight; 
//If there is little content, exit the function directly
if(oUl_h<target.offsetHeight) return; 

target.innerHTML += target.innerHTML; 

 
//Pull function function out, convenient call
var fn = function(){ 
if(target.scrollTop == oUl_h){ 
target.scrollTop = 0; 
}else{ 
target.scrollTop++; 
} 
} 
//SetInterval cycle
var timer = setInterval(function(){ 
fn(); 
},30); 
// hover 
target.onmouseover = function(){ 
clearTimeout(timer); 
} 
target.onmouseout = function(){ 
timer = setInterval(function(){ 
fn(); 
},30); 
} 
})(); 

A simple vertical seamless slot has been completed. To meet more requirements, it is recommended to encapsulate functions that can be called vertically, horizontally, and multiple times.

The following is an online example of personal encapsulation:

http://lgyweb.com/marScroll/

 
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;n<i;n++){ 
if(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 = '<div class="J_scrollInner">'+holderHTML+'</div>'; 
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; 
} 
} 
}