javascript实现瀑布流动态加载图片原理

时间:2020-05-15 回忆没了焦点人气:0

本文实例为大家分享了js瀑布流加载效果，动态加载图片，供大家参考，具体内容如下

鼠标滚动事件，当鼠标滚动到下边，动态加载图片。

1. HTML代码

<!DOCTYPE html>
<html>
 <head>
  <meta charset="UTF-8">
  <title>js实现瀑布流效果-动态加载图片</title>
  <link rel="stylesheet" href="css/waterfallflow.css" type="text/css" />
  <script src="js/waterfallflow.js"></script>
 </head>
 <body>
  <div id="container">
   <div class="box">
    <div class="box_img">
     <img src="img/1.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/2.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/3.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/4.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/5.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/6.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/7.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/3.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/1.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/2.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/1.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/2.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/3.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/4.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/5.jpg" />
    </div>
   </div>
   <div class="box">
    <div class="box_img">
     <img src="img/6.jpg" />
    </div>
   </div>
    
  </div>
 </body>
</html>

2. CSS代码

*{
 margin: 0px;
 padding: 0px;
}
#container{
 position: relative;
}
.box{
 padding: 5px;
 float: left;
 margin: 0px auto;
}
.box_img{
 padding: 5px;
 border: 1px solid #DCDCDC;
 box-shadow: 0 0 5px #ccc;
 border-radius: 5px;
}
.box_img img{
 width: 230px;
}

3. JavaScript代码

window.onload=function(){
  
 imgLocation("container","box");
 var imgData={"data":[{"src":"1.jpg"},{"src":"2.jpg"},{"src":"3.jpg"},{"src":"3.jpg"},{"src":"4.jpg"},{"src":"5.jpg"},{"src":"6.jpg"},{"src":"2.jpg"},{"src":"3.jpg"},{"src":"3.jpg"},{"src":"4.jpg"},{"src":"5.jpg"}]}
 window.onscroll=function(){
//  console.log(document.documentElement.scrollTop);
  if(checkFlag()){
   var cparent=document.getElementById("container");
   for(var i=0;i<imgData.data.length;i++){
    var ccontent=document.createElement("div");
    ccontent.className="box";
    cparent.appendChild(ccontent);
    var boximg=document.createElement("div");
    boximg.className="box_img";
    ccontent.appendChild(boximg);
    var img=document.createElement("img");
    img.src="img/"+imgData.data[i].src;
    boximg.appendChild(img);
     
    //另外一种方法在div后边追加内容，不覆盖原有内容
//    var content="<div class='box'><div class='box_img'><img src='img/"+imgData.data[i].src+"'/></div></div>";
//    cparent.innerHTML+=content;
   }
   imgLocation("container","box");
  }
 }
}
 
function checkFlag(){
 var cparent=document.getElementById("container");
 var ccontent=getChildElement(cparent,"box");//图片的所有box数
 var lastContentHeight=ccontent[ccontent.length-1].offsetTop;//最后一张图片距离顶部高度
 var scrollTop=document.documentElement.scrollTop||document.body.scrollTop;//滚动条距离顶部高度
 var pageHeight=document.documentElement.clientHeight||document.body.clientHeight;//屏幕高度
// console.log(lastContentHeight+","+scrollTop+","+pageHeight);
 if(lastContentHeight<scrollTop+pageHeight){
  return true;
 }
}
 
function imgLocation(parent,content){
 var cparent=document.getElementById(parent);
 var ccontent=getChildElement(cparent,content);//图片的所有box数
 var imgWidth=ccontent[0].offsetWidth;//图片宽度
 var num=Math.floor(document.documentElement.clientWidth/imgWidth);//一行放图片个数
 cparent.style.cssText="width:"+imgWidth*num+"px;margin:0px auto";//container的宽度
 var boxHeightArr=[];//每一列box高度
 for(var i=0;i<ccontent.length;i++){
  if(i<num){
   boxHeightArr[i]=ccontent[i].offsetHeight;
  }else{
   var minHeight=Math.min.apply(null,boxHeightArr);//最小高度
   var minIndex = getMinheightLocation(boxHeightArr,minHeight);//得到最小高度下标
//   console.log(minHeight+","+minIndex);
   ccontent[i].style.position="absolute";
   ccontent[i].style.top=minHeight+"px";//距离顶部高度
   ccontent[i].style.left=ccontent[minIndex].offsetLeft+"px";//距离左边长度
   boxHeightArr[minIndex]+=ccontent[i].offsetHeight;
//   console.log(ccontent[i].offsetHeight+","+ccontent[i].height);//ccontent[i].height=undefined
    
  }
 }
}
 
function getMinheightLocation(boxHeightArr,minHeight){
 for(var i in boxHeightArr){
  if(boxHeightArr[i]==minHeight){
   return i
  }
 }
}
 
function getChildElement(parent,content){
 //将parent下有content的全部取出
 var contentArr=[];
 var allContent=parent.getElementsByTagName("*");
 for(i=0;i<allContent.length;i++){
  if(allContent[i].className=="box"){
   contentArr.push(allContent[i]);
  }
 }
 return contentArr;
}

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