js --迭代器模式

var Iterator = function(items,container){
var container = container && document.getElementById(container)||document,
items = container.getElementByTagName(items),length = items.length,index = 0 ;
var splice = [].splice;
return {
first:function(){
index = 0 ;
return items[index]
},
last:function(){
index = length -1 ;
return items[index];
},
pre:function(){
if(--index > 0){
return items[index]
}else{
index = 0 ;
return items[index];
}
},
next:function(){
if(++index < length){
return items[index];
}else{
index = length - 1;
return null;
}
},
get:function(num){
index = num > 0 ? num % length:num % length+length;
return items[index]
},
dealEach:function(fn){
var args = splice.call(arguments,1);
for(var i = 0 ; i < length ; i++){
fn.apply(items[i],args);
}
},
dealItem:function(num,fn){
fn.apply(this.get(num),splice.call(arguments,2));
},
exclusive:function(num,allFn,numFn){
this.dealEach(allFn);
if(Object.prototype.toString.call(num) === "[object Array]"){
for(var i = 0 ; len = num.length ; i < len ; i ++){
this.dealITem(num[i],numFn);
}
}else{
this.dealItem(num,numFn);
}
}
}
}