javascript-实现简单瀑布流

直接上代码：

<style>
*{ 
	margin:0; 
	padding:0;
}	
.waterfall_item{
	border:solid 3px #ccc;
	box-shadow:1px 1px 3px #eee;
	border-radius:8px;
	font:normal 12px/22px 'Microsoft yahei';
	text-align: center;
	padding: 20px 0;
	overflow: hidden;
}
</style>


<script>
/**
	瀑布流
	分析：
		瀑布流主要解决各个列的各元素的位置，以及各列的高度问题
*/
/**
	瀑布流
	分析：		
		瀑布流主要解决各个列的各元素的位置，以及各列的高度问题
	确定一行有几列，每个元素之间的间隔大小。
	获取各元素的高度，添加到面板，并确定每列的高度
	属性：
		panel//画板
		items//要加载的项目
		colNum//列数
		col=[]//列数组
		colLeft// 左间距
		colTop// 上间距
	方法:
		init//初始化
		refresh//刷新
		setColNum//设置列数
		setColLeft//设置左间距
		setColTop//设置上间距
		paint//添加到外框
		refreshPanel//更新外部画板
		
*/
function getStyle(o,name){
	if(document.defaultView&&document.defaultView.getComputedStyle)
		return document.defaultView.getComputedStyle(o,null)[name];
	else
		return o.currentStyle[name];
}
function waterfall(opts){
	this.init(opts);	
}
waterfall.prototype={
	constructor:waterfall,
	init:function(opts){
		this.panel=opts.panel||document.body;//画板
		this.items=opts.items||[];//要加载的项目
		this.colNum=opts.colNum||3;//列数
		this.colLeft=opts.colLeft||5;//左间距
		this.colTop=opts.colTop||5;// 上间距
		this._updated=false;
		this.col=[];
		this.initCol();
		this.newItems=this.items;
		this.draw(this.newItems);
	},
	initCol:function(){
		//初始化列数组
		for(var i=0,len=this.colNum;i<len;i++){
			this.col[i]={
				height:0,//高度
				itemNum:0,//项目数
				idx:i,
				count:0
			}
		}		
	},
	refresh:function(type){
		var items;
		if(this._updated){
			if(type!=='append'){
				this.initCol();
				this.panel.innerHTML='';
				items=this.items;
			}else{
				items=this.newItems;	
			}
			this.draw(items);
		}
	},
	_setUpdate:function(updated){
		if(this._updated!=updated){
			this._updated=updated;
		}
	},
	setColNum:function(num){
		if(num==this.colNum)return;
		this._setUpdate(true);
		this.colNum=num;
	},
	setColLeft:function(leftSpan){
		this._setUpdate(true);
		this.colLeft=leftSpan;
	},
	setColTop:function(topSpan){
		this._setUpdate(true);
		this.colLeft=leftSpan;	
	},
	addItems:function(items){
		this._setUpdate(true);
		this.items=this.items.concat(items);
		this.newItems=items;
	},
	draw:function(items){
		var that=this,
			i=0,
			p=this.panel,
			len=items.length;
		for(;i<len;i++){
			var r=Math.floor(i/this.colNum);
			var w=parseInt(getStyle(p,'width'))/this.colNum-this.colLeft;			
			var curCol=this.getMinHeightCol();
			var c=curCol.idx;
			var t=curCol.height+this.colTop;
			var l=c*(w+this.colLeft)+this.colLeft;		
			var oitem=this.createItem(w,l,t,items[i]);
			p.appendChild(oitem);
			var itemH=oitem.offsetHeight;
			curCol.height=curCol.height+itemH+this.colTop;
			curCol.count++;
			p.style.height=curCol.height+'px';
		}
	},
	createItem:function(w,l,t,html){
		var oitem=document.createElement('div');
		oitem.innerHTML=html;
		oitem=oitem.firstChild;
		oitem.style.position='absolute';
		oitem.style.width=w+'px';
		oitem.style.left=l+'px';
		oitem.style.top=t+'px';
		return oitem;
	},
	getMinHeightCol:function(){
		var idx=0,minner=this.col[idx].height;
		for(var i=0,len=this.colNum;i<len;i++){			
			if(minner>this.col[i].height){				
				minner=this.col[i].height;
				idx=i;	
						
			}					
		}
		return this.col[idx];
	}
}

</script>
<div style="margin:0 auto">列：<input type="text" value='3' id="col_num" /><button id="refresh">刷新</button></div>
<div id="response_flow" class="response_flow"  style="1000px;position:relative;">
	
</div>
<script>
//测试用例
var items=[
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		    "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' style='height:100px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='1.jpg' height='200' style='height:200px;' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>"
		  ]
var colNum;
var refreshBtn=document.getElementById('refresh');

var panel=document.getElementById('response_flow');

var flow=new waterfall({
					   panel:panel,
					   items:items,
					   colLeft:20,
					   topLeft:20
					  })
//追加
var newItems=[
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='100' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'><img src='http://sandbox.runjs.cn/uploads/rs/392/w5zrkmek/1.jpg' height='200' /><br />asdfasdfasdf</div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>",
		   "<div class='waterfall_item'>asdfasdfasdf<br />asdfasdfasdf<br /></div>" 
];


refreshBtn.onclick=function(){
	colNum=document.getElementById('col_num').value;
	flow.setColNum(colNum);
	flow.refresh();
}
var toop=200;
var loadNum=1;
var maxNum=5;
var originTop=document.body.scrollHeight-document.documentElement.clientHeight;
window.onscroll=function(){
	var to=document.body.scrollTop;
	if(loadNum>maxNum)return;
	if(to>loadNum*toop){
		loadNum++;
		flow.addItems(newItems)
		flow.refresh('append')
	}
}
window.onresize=function(){
	flow._setUpdate(true);
	flow.refresh();	
}

</script>

效果见：