javascript Waterfall streaming image lazy load instance

Lazy loading has been used in recent projects, but update 1 is now common, since zepto.js is usually used for mobile development. It can also be used with jQuery.

The code is as follows:

/**
 * Created by zhiqiang on 2015/10/14.
 * hpuhouzhiqiang@gmail.com
 *  Lazy loading of pictures 
 **/
function loadImgLazy(node) {
 var lazyNode = $('[node-type=imglazy]', node),
 mobileHeight, lazyOffSetHeight, tempHeight, currentNodeTop, imgObject,
 imgDataSrc, localUrl;

 localUrl = location.href;
 //  Gets the height of the current browser's visual area 
 mobileHeight = $(window).height();

 return function(co) {

 var conf = {
 'loadfirst': true,
 'loadimg': true
 };

 for (var item in conf) {
 if (item in co) {
 conf[item] = co[item];
 }
 }

 var that = {};
 var _this = {};
 /**
 * [replaceImgSrc  Dynamic replacement in nodes src]
 * @param {[type]} tempObject [description]
 * @return {[type]} [description]
 */
 _this.replaceImgSrc = function(tempObject) {
 var srcValue;

 $.each(tempObject, function(i, item) {
 imgObject = $(item).find('img[data-lazysrc]');
 imgObject.each(function(i) {
  imgDataSrc = $(this).attr('data-lazysrc');
  srcValue = $(this).attr('src');
  if (srcValue == '#') {
  if (imgDataSrc) {
  $(this).attr('src', imgDataSrc);
  $(this).removeAttr('data-lazysrc');
  }
  }
 });
 });
 };

 /**
 *  The first screen determines whether it appears on the screen imglazy Nodes, if any, load images 
 * @param {[type]} i) {  currentNodeTop [description]
 * @return {[type]} [description]
 */
 _this.loadFirstScreen = function() {
 if (conf.loadfirst) {
 lazyNode.each(function(i) {
  currentNodeTop = $(this).offset().top;
  if (currentNodeTop < mobileHeight + 800) {
  _this.replaceImgSrc($(this));
  }
 });
 }
 };

 // When the first screen is loaded, load the image as a queue 
 _this.loadImg = function() {
 if (conf.loadimg) {
 $(window).on('scroll', function() {
  var imgLazyList = $('[node-type=imglazy]', node);
  for (var i = 0; i < 5; i++) {
  _this.replaceImgSrc(imgLazyList.eq(i));
  }
 });
 }
 };

 that = {
 replaceImgSrc: _this.replaceImgSrc(),
 mobileHeight: mobileHeight,
 objIsEmpty: function(obj) {
 for (var item in obj) {
  return false;
 }
 return true;
 },
 destory: function() {
 if (_this) {
  $.each(_this, function(i, item) {
  if (item && item.destory) {
  item.destory();
  }
  });
  _this = null;
 }
 $(window).off('scroll');
 }
 };
 return that;
 };
}

I hope this article is helpful for you to learn the lazy loading of javascript images.