详解javascript实现瀑布流绝对式布局

var $ = function() {
  return document.querySelectorAll.apply(document, arguments);
 }
 var arrHeight = []; //得到分列的高度
 var columns = function() { //计算页面最多可以放多少列
  var containerW = $("#main")[0].clientWidth,
   pinW = $(".pin")[0].offsetWidth;
  return Math.floor(containerW / pinW);
 }
 var getIndex = function(arr) { //获得最小高度的index
   var minHeight = Math.min.apply(null, arr); //获得最小高度
   for (var i in arr) {
    if (arr[i] === minHeight) {
     return i;
    }
   }
  }
  //根据列数确定第一排img的高度并放入数组当中。
 var setCenter = (function() { //通过列数设置宽度
  var main = $('#main')[0]; //获得罩层
  var getPadding = function() { //设置padding
   var col = columns(); //获得最后一列
   var padding = main.clientWidth - col * $('.pin')[0].offsetWidth;
   return padding / 2;
  }
  var getComputedStyle = function(ele) { //兼容IE的支持情况
   if (window.getComputedStyle) {
    return window.getComputedStyle(ele);
   } else {
    return ele.currentStyle;
   }
  }
  var getPinPad = function() { //获得pin的padding值
   var pin = $(".pin")[0];
   return parseInt(getComputedStyle(pin).paddingLeft);
  }
  return function() { //设置宽度
   main.style.padding = `0 ${getPadding()}px 0 ${getPadding()-getPinPad()}px`;
  }
 })();
 var overLoad = function(ele) {
  var index = getIndex(arrHeight),
   minHeight = Math.min.apply(null, arrHeight), //获取最小高度
   pins = $('.pin'),
   style = ele.style;
  style.position = "absolute";
  style.top = minHeight + "px"; //设置当前元素的高度
  style.left = pins[index].offsetLeft + "px";
  arrHeight[index] += ele.offsetHeight;
 }
 //初始化时执行函数
 var init = function() {
   var pins = $(".pin"),
    col = columns();
   setCenter(); //设置包裹容器的宽度
   for (var i = 0, pin; pin = pins[i]; i++) {
    if (i < col) { //存储第一排的高度
     arrHeight.push(pin.offsetHeight);
    } else {
     overLoad(pin); //将元素的位置重排
    }
   }
  }

var overLoad = function(ele) {
  var index = getIndex(arrHeight),
   minHeight = Math.min.apply(null, arrHeight), //获取最小高度
   pins = $('.pin'),
   style = ele.style;
  style.position = "absolute";
  style.top = minHeight + "px"; //设置当前元素的高度
  style.left = pins[index].offsetLeft + "px";
  arrHeight[index] += ele.offsetHeight;
 }

var dataInt = [{
  'src': '1.jpg'
 }, {
  'src': '2.jpg'
 }, {
  'src': '3.jpg'
 }, {
  'src': '4.jpg'
 }, {
  'src': '1.jpg'
 }, {
  'src': '2.jpg'
 }, {
  'src': '3.jpg'
 }, {
  'src': '4.jpg'
 }];

 function isLoad() { //是否可以进行加载
  var scrollTop = document.documentElement.scrollTop || document.body.scrollTop,
   wholeHeight = document.documentElement.clientHeight || document.body.clientHeight,
   point = scrollTop + wholeHeight; //页面底部距离header的距离
  var arr = $('.pin');
  var lastHei = arr[arr.length - 1].getBoundingClientRect().top;
  return (lastHei < point) ? true : false;
 }
 //处理滑动
 var dealScroll = (function() {
  var main = $('#main')[0],
   flag = true;
  return function() {
   if (isLoad() && flag) {
    for (var i = 0, data; data = dataInt[i++];) {
     var div = document.createElement('div');
     div.innerHTML = temp(data.src);
     div.className = "pin";
     main.appendChild(div);
     overLoad(div); //和上面的overload有耦合性质
    }
    flag = false;
    setTimeout(function() { //控制滑行手速，时间越长对速度的滑动时间影响越大。
     flag = true;
    }, 200);
   }
  }
 })();

 function temp(src) {
  return `
  <div class="box">
   <img src="http://cued.xunlei.com/demos/publ/img/P_00${src}"/>
  </div>
 `;
 }

 function isLoad() { //是否可以进行加载
  var scrollTop = document.documentElement.scrollTop || document.body.scrollTop,
   wholeHeight = document.documentElement.clientHeight || document.body.clientHeight,
   point = scrollTop + wholeHeight; //页面底部距离header的距离
  var arr = $('.pin');
  var lastHei = arr[arr.length - 1].getBoundingClientRect().top;
  return (lastHei < point) ? true : false;
 }

 var resize = (function() {
   var flag;
   return function(fn) {
    clearTimeout(flag);
    flag = setTimeout(function() { //函数的节流,防止用户过度移动
     fn();
     console.log("ok")
    }, 500);
   }
})();

 var update = function(ele) { //当resize的时候，重新设置
  ele.style.position = "initial";
 }
 //初始化时执行函数
 var init = function() {
   var pins = $(".pin"),
    col = columns();
   arrHeight = []; //清空高度
   setCenter(); //设置包裹容器的宽度
   for (var i = 0, pin; pin = pins[i]; i++) {
    if (i < col) { //存储第一排的高度
     arrHeight.push(pin.offsetHeight);
     update(pin);
    } else {
     overLoad(pin); //将元素的位置重排
    }
   }
  }