以HTML5的文件上传API
如下demo代码在.html文件打开即可：
!DOCTYPE html> <html lang="zh_cn"> <head> <meta charset="UTF-8"> <title>HTML5文件上传FileReader API</title> </head> <body> <!--一个能上传多媒体文件的表单--> <input type="file" id="upload-file" multiple /> <!--显示图片的地方--> <div id="destination"></div> <script> document.getElementById('upload-file').addEventListener('change', function() { var file; var destination = document.getElementById('destination'); destination.innerHTML = '';//每次清空内容 // 循环用户多选的文件 for(var x = 0, xlen = this.files.length; x < xlen; x++) { file = this.files[x]; console.log(file); if(file.type.indexOf('image') != -1) { // 非常简单的交验，判断文件是否是图片 var reader = new FileReader();//文件预览对象 reader.readAsDataURL(file);//设置要预览的文件 reader.onload = function(e) {//监听文件加载完成事件 var img = new Image();//创键预览图片 img.src = e.target.result; //把预览图片的src设置为e.target.result属性。返回预览文件的二进制内存数据 destination.appendChild(img);//在把每张图片，放到预览区域 }; } } }); </script> </body> </html>
一、input:file属性
属性值有以下几个比较常用：
accept：表示可以选择的文件MIME类型，多个MIME类型用英文逗号分开，常用的MIME类型见下表。
multiple：是否可以选择多个文件，多个文件时其value值为第一个文件的虚拟路径。
1、accept
只能选择png和gif图片
<input id="fileId1" type="file" accept="image/png,image/gif" name="file" />2、multiple
多选文件上传
<input id="fileId2" type="file" multiple="multiple" name="file" />3、常用MIME类型
后缀名 MIME名称 *.3gpp audio/3gpp, video/3gpp *.ac3 audio/ac3 *.asf allpication/vnd.ms-asf *.au audio/basic *.css text/css *.csv text/csv *.doc application/msword *.dot application/msword *.dtd application/xml-dtd *.dwg image/vnd.dwg *.dxf image/vnd.dxf *.gif image/gif *.htm text/html *.html text/html *.jp2 image/jp2 *.jpe image/jpeg *.jpeg image/jpeg *.jpg image/jpeg *.js text/javascript, application/javascript *.json application/json *.mp2 audio/mpeg, video/mpeg *.mp3 audio/mpeg *.mp4 audio/mp4, video/mp4 *.mpeg video/mpeg *.mpg video/mpeg *.mpp application/vnd.ms-project *.ogg application/ogg, audio/ogg *.pdf application/pdf *.png image/png *.pot application/vnd.ms-powerpoint *.pps application/vnd.ms-powerpoint *.ppt application/vnd.ms-powerpoint *.rtf application/rtf, text/rtf *.svf image/vnd.svf *.tif image/tiff *.tiff image/tiff *.txt text/plain *.wdb application/vnd.ms-works *.wps application/vnd.ms-works *.xhtml application/xhtml+xml *.xlc application/vnd.ms-excel *.xlm application/vnd.ms-excel *.xls application