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/vnd.ms-excel ???*.xlt ?????application/vnd.ms-excel ???*.xlw ?????application/vnd.ms-excel ???*.xml ???text/xml, application/xml ???*.zip ???????????aplication/zip ???*.xlsx ????application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

二、样式美化

请看博客：css input[type=file] 样式美化，input上传按钮美化 http://www.haorooms.com/post/css_input_uploadmh

三、AJAX上传文件

在说到ajax上传文件。ajax上传的时候，需要获得input:file选择的文件（可能为多个文件），获取其文件列表为：

// input标签的files属性document.querySelector("#fileId").files// 返回的是一个文件列表数组

获得的文件列表，然后遍历插入到表单数据当中。即：

// 获得上传文件DOM对象var oFiles = document.querySelector("#fileId");// 实例化一个表单数据对象var formData = new FormData();// 遍历图片文件列表，插入到表单数据中for (var i = 0, file; file = oFiles[i]; i++) { ???// 文件名称，文件对象 ???formData.append(file.name, file);}

获得表单数据之后，就可以用ajax的POST上传。

// 实例化一个AJAX对象var xhr = new XMLHttpRequest();xhr.onload = function() { ???alert("上传成功！");}xhr.open("POST", "upload.php", true);// 发送表单数据xhr.send(formData);

上传到服务器之后，获取到文件列表为：

Array( ???[jpg_jpg] => Array ???????( ???????????[name] => jpg.jpg ???????????[type] => image/jpeg ???????????[tmp_name] => D:\xampp\tmp\phpA595.tmp ???????????[error] => 0 ???????????[size] => 133363 ???????) ???[png_png] => Array ???????( ???????????[name] => png.png ???????????[type] => image/png ???????????[tmp_name] => D:\xampp\tmp\phpA5A6.tmp ???????????[error] => 0 ???????????[size] => 1214628 ???????))

在服务端循环遍历这个数组就可以上传文件了。