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Javascript implements waterfall flow to dynamically load images

不言
不言Original
2018-06-25 15:27:012513browse

This article mainly introduces in detail the principle of dynamic loading of images using JavaScript to implement waterfall flow. It has a certain reference value. Interested friends can refer to it.

The example in this article shares the js waterfall with everyone. Stream loading effect, dynamic loading of pictures, for your reference, the specific content is as follows

Mouse scroll event, when the mouse scrolls to the bottom, the picture is dynamically loaded.

1. HTML code

##

<!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>
  <p id="container">
   <p class="box">
    <p class="box_img">
     <img src="img/1.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/2.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/3.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/4.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/5.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/6.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/7.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/3.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/1.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/2.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/1.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/2.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/3.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/4.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/5.jpg" />
    </p>
   </p>
   <p class="box">
    <p class="box_img">
     <img src="img/6.jpg" />
    </p>
   </p>
    
  </p>
 </body>
</html>

2. CSS code 

*{
 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 code 

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("p");
    ccontent.className="box";
    cparent.appendChild(ccontent);
    var boximg=document.createElement("p");
    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p后边追加内容，不覆盖原有内容
//    var content="<p class=&#39;box&#39;><p class=&#39;box_img&#39;><img src=&#39;img/"+imgData.data[i].src+"&#39;/></p></p>";
//    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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