Js图片等比例缩放

 ???<img src="chargein_cashgift_detail.png" class="img" >function showImg(img,maxW,maxH) { ???let objImg = new Image(); ???let w,h,wRatio,hRatio; ???let Ratio =1; //比率 ???objImg.src=img.src; ???if(img.naturalWidth){ ???????w =img.naturalWidth; ???????h =img.naturalHeight; ???}else{ ???????w =objImg.width; ???????h =objImg.height; ???} ???wRatio = maxW / w; ???hRatio = maxH / h; ???if(maxW === 0 && maxH ===0){ ???????Ratio = 1; ???}else if(maxW === 0){ ???????if(hRatio<1) { ???????????Ratio = hRatio; ???????} ???}else if (maxH === 0){ ???????if(wRatio<1){ ???????????Ratio = wRatio; ???????} ???}else if (wRatio<1 || hRatio<1){ ???????Ratio = (wRatio<=hRatio?wRatio:hRatio); ???} ???if (Ratio<1){ ???????w = w * Ratio; ???????h = h * Ratio; ???} ???img.width =w; ???img.height =h; ???console.log(w) ???console.log(h)}let img1 =document.querySelectorAll(‘img‘)[0]showImg(img1,300,200)