图片懒加载
<!DOCTYPE html> <html lang="en" class="app"> <head> <meta charset="utf-8"/> <title>懒加载</title> </head> <script>window.Echo=(function(window,document,undefined){'use strict';var store=[],offset,throttle,poll;var _inView=function(el){var coords=el.getBoundingClientRect();return((coords.top>=0&&coords.left>=0&&coords.top)<=(window.innerHeight||document.documentElement.clientHeight)+parseInt(offset));};var _pollImages=function(){for(var i=store.length;i--;){var self=store[i];if(_inView(self)){self.src=self.getAttribute('data-echo');store.splice(i,1);}}};var _throttle=function(){clearTimeout(poll);poll=setTimeout(_pollImages,throttle);};var init=function(obj){var nodes=document.querySelectorAll('[data-echo]');var opts=obj||{};offset=opts.offset||0;throttle=opts.throttle||250;for(var i=0;i<nodes.length;i++){store.push(nodes[i]);}_throttle();if(document.addEventListener){window.addEventListener('scroll',_throttle,false);}else{window.attachEvent('onscroll',_throttle);}};return{init:init,render:_throttle};})(window,document); </script> <style> .demo img { width: 736px; height: 490px; background: url(images/loading.gif) 50% no-repeat; } .lazy{ width: 500px; height: 500px; } </style> <body> <div class="demo"> <img class="lazy" src="__STATIC__/leave/image/small.png" data-echo="__STATIC__/leave/image/big.jpg"> </div> </body> </html> <script> Echo.init({ offset: 0,//离可视区域多少像素的图片可以被加载 throttle: 0 //图片延时多少毫秒加载 }); </script>