原生js 懒加载
2018-05-23 本文已影响4人
加冰宝贝
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<!-- <script src="https://unpkg.com/axios/dist/axios.min.js"></script> -->
<style>
<!--css样式 -->
#main {
position: relative;
}
#main div {
float: left;
width: auto;
height: auto;
}
#main img {
padding: 10px;
width: 180px;
height: auto;
}
</style>
</head>
<body>
<!--HTML样式 -->
<div id="main"></div>
<!--js样式 -->
<script>
//此加载出来的图片 是找的接口 不要介意呦\(^o^)/~
window.onload = function () {
http();
}
// 定义函数是为了在图片加载完成之后调用 否则获取不了高度
function layout(id,tag,img) {
// showImg 滚动执行函数
window.onscroll = showImg
var oMain = document.getElementById(id);
var oDiv = oMain.getElementsByTagName(tag);
var oImg = oMain.querySelectorAll(img);
imgPush(oMain,oDiv,oImg);
}
// 设置大盒子的宽度
function imgPush(oMain,oDiv,oImg){
var oimg = [];
for (var i = 0; i < oImg.length; i++) {
oimg.push(oImg[i]);
}
var width = oimg[0].offsetWidth;
var DocuW = document.documentElement.clientWidth;
var list = Math.floor(DocuW / width);
oMain.style.cssText = "width:" + list * width + "px; margin: 0 auto;";
loca(oDiv,list,width);
}
// 让每个图片去该去的地方
function loca(oDiv,list,width){
var Height = [];
for (var j = 0; j < oDiv.length; j++) {
if (j < list) {
Height[j] = oDiv[j].offsetHeight
} else {
var minH = Math.min.apply(null, Height);
oDiv[j].style.position = 'absolute';
oDiv[j].style.top = minH + 'px';
oDiv[j].style.left = index() * width + 'px';
Height[index()] += oDiv[j].offsetHeight;
}
}
// 获取每回遍历最小值的下标
function index() {
for (var h = 0; h < Height.length; h++) {
if (Height[h] == minH) {
return h;
}
}
}
}
// 请求图片服务器 渲染页面
function http() {
var xhr = new XMLHttpRequest();
xhr.open("GET", "https://www.apiopen.top/meituApi", true);
xhr.send();
var Main = document.getElementById("main");
xhr.onreadystatechange = function () {
if (xhr.readyState == 4 && xhr.status == 200) {
var data = JSON.parse(xhr.responseText).data
for (var i = 0; i < data.length; i++){
var img = document.createElement("img");
var div = document.createElement("div");
img.src = data[i].url;
div.appendChild(img);
Main.appendChild(div);
}
// 当最后一个图片加载完毕 从新排序
var img = document.getElementsByTagName("img");
var subscript = img.length -1;
img[subscript].onload = function () {
layout('main','div','img')
}
}
}
}
//滚动事件
function showImg(){
var scollH = document.documentElement.scrollTop;
var cliH = document.documentElement.clientHeight;
var H = document.documentElement.scrollHeight;
if(H - scollH <= cliH + 150 ){
http();
}
}
</script>
</body>
</html>
