图片懒加载

let imageList = [...document.querySelectorAll('img')];

let num = imageList.length;

let lazyLoad1 =(()=>{

let count = 0;

return function(){

let newArr = [];

imageList.forEach((item, index) =>{

let rect = item.getBoundingClientRect();

if(rect.top < window.innerHeight){

rect.src = rect.dataset.src;

newArr.push(index);

count++;

if(count === num){

document.removeEventListener('scroll', lazyLoad1);

}

}

});

//删除已加载完的图片

imagelist = imageList.filter( (_ , index) => !newArr.includes(index))

}

})();

//在这里调用throttle的节流函数

lazyLoad1 = Proxy(lazyLoad1, 100);

document.addEventListener('scroll', lazyLoad1);

//手动执行一次，加载首屏图片

lazyLoad1();