console.log(clos)输出列数为7，浏览器显示为6列，且前第七个和第八个图片（第二列的一和二）没有内边距

// JavaScript Document

window.onload=function(){

waterfall("main","box");

}

function waterfall(parent,box){

var oParent=document.getElementById(parent);

getByClass(oParent,box);

var oBoxs=getByClass(oParent,box);

var aBoxW=oBoxs[0].offsetWidth;

var cols=Math.floor(document.documentElement.clientWidth/aBoxW);

oParent.style.cssText='width:'+aBoxW*cols+'px;margin:auto';

var hArr=[];

for(var i=0;i<oBoxs.length;i++){

if(i<cols-1){

hArr.push(oBoxs[i].offsetHeight);

}else{

var minH=Math.min.apply(null,hArr);

var index=getMinHIndex(hArr,minH);

oBoxs[i].style.position="absolute";

oBoxs[i].style.top=minH+'px';

//oBoxs[i].style.left=aBoxW*index+'px';

oBoxs[i].style.left=oBoxs[index].offsetLeft+'px';

hArr[index]+=oBoxs[i].offsetHeight;

}

}

console.log(cols);

console.log(hArr);

}

function getByClass(parent,clsName){

var boxArr=[];

oElements=parent.getElementsByTagName("*");

for(var i=0;i<oElements.length;i++){

if(oElements[i].className==clsName){

boxArr.push(oElements[i]);

}

}

return boxArr;

}

function getMinHIndex(arr,val){

for(var i in arr){

if(arr[i]==val){

return i;

}

}

}