前端：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> <img src="" id='myimg' width="50" height="50"> <script type="text/javascript"> //先让浏览器加载img标签，然后在JS中为img标签指定图片 document.getElementById("myimg").src="vichin.jpg"; </script> </body> </html>
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> </head> <body> <div>添加图片缓存</div> <img src="vichin.jpg" id="img2" width="100" height="100"> <script type="text/javascript"> window.onload=function () { var myimgs=new Image(); myimgs.src="vichin.jpg" myimgs.onload=function () { alert('hi、vichin!'); } } //这样图片只会在页面初次请求时被加载 </script> </body> </html>