<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> <title>js图片预览功能</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" onchange="previewFile()"><br> <img src="" height="200" width="300" alt="Image preview..."/> </body> </html>
原文：http://www.cnblogs.com/whboxl/p/7985622.html