<html> <head> <meta content="text/html" /> <title>图片预览</title> <script language=javascript> function previewFile() { var preview = document.querySelector('img'); var file = document.querySelector('input[type=file]').files[0]; var reader = new FileReader(); reader.onloadend = function () { preview.src = reader.result; } if (file) { reader.readAsDataURL(file); } else { preview.src = ""; } } </script> </head> <body> <input type="file" οnchange="previewFile()"><br> <img src="" height="400" width="600" alt="未选择图片"/> </body> </html>