const target = e.target,
h = target.naturalHeight,
w = target.naturalWidth,
r = h / w,
height = window.innerHeight || window.screen.availHeight,
width = window.innerWidth || window.screen.availWidth,
rate = height / width;
let imgStyle = {};
if(r >= 3.5){
// imgStyle.width = width + "px";
// imgStyle.height = h * width / w + "px";
target.setAttribute('long', true);
}
// 图片的高宽比大于屏幕的高宽比，则图片的高度取屏幕的高度
// 图片的高宽比小于屏幕的高宽比，则图片的宽度取屏幕的宽度
if(r > rate){
imgStyle.height = height + "px";
imgStyle.width = w * height / h + "px";
imgStyle.left = width / 2 - (w * height / h) / 2 + "px";
}else if( r < rate){
imgStyle.width = width + "px";
imgStyle.height = h * width / w + "px";
imgStyle.top = height / 2 - (h * width / w) / 2 + "px"
} else {
imgStyle.width = width;
imgStyle.height = height;
}
target.setAttribute('style', `width:${imgStyle.width}; height:${imgStyle.height}; left:${imgStyle.left}; top:${imgStyle.top};`);
target.setAttribute('rate', 1/r);
