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目录
- 基本思路
- 示例
[一]、基本思路
在FireFox、Chrome浏览器中可以根据document.getElementById(“id_file”) .files[0].size获取上传文件的大小（字节数），而IE浏览器中不支持该属性，只能借助<img >标签的dynsrc属性，来间接实现获取文件的大小（但需要同意ActiveX控件的运行）。
[二]、示例
测试代码：filesize-check.html
1 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"" "> |
2 | < html xmlns = " " > |
3 | < head > |
4 | < meta name = "DEscription" contect = "my code demo" /> |
5 | < meta name = "Author" contect = "Michael@www.micmiu.com" /> |
6 | < meta http-equiv = "Content-Type" content = "text/html; charset=utf-8" /> |
7 | < title >js check file size @ www.micmiu.com</ title > |
8 | </ head > |
9 | < body > |
10 | < img id = "tempimg" dynsrc = "" src = "" style = "display:none" /> |
11 | < input type = "file" name = "file" id = "fileuploade" size = "40" /> |
12 | < input type = "button" name = "check" value = "checkfilesize" onclick ="checkfile()" /> |
13 |
14 | </ body > |
15 | < script type = "text/javascript" > |
16 | var maxsize = 2*1024*1024;//2M |
17 | var errMsg = "上传的附件文件不能超过2M！！！"; |
18 | var tipMsg = "您的浏览器暂不支持计算上传文件的大小，确保上传文件不要超过2M，建议使用IE、FireFox、Chrome浏览器。"; |
19 | var browserCfg = {}; |
20 | var ua = window.navigator.userAgent; |
21 | if (ua.indexOf("MSIE")>=1){ |
22 | browserCfg.ie = true; |
23 | }else if(ua.indexOf("Firefox")>=1){ |
24 | browserCfg.firefox = true; |
25 | }else if(ua.indexOf("Chrome")>=1){ |
26 | browserCfg.chrome = true; |
27 | } |
28 | function checkfile(){ |
29 | try{ |
30 | var obj_file = document.getElementById("fileuploade"); |
31 | if(obj_file.value==""){ |
32 | alert("请先选择上传文件"); |
33 | return; |
34 | } |
35 | var filesize = 0; |
36 | if(browserCfg.firefox || browserCfg.chrome ){ |
37 | filesize = obj_file.files[0].size; |
38 | }else if(browserCfg.ie){ |
39 | var obj_img = document.getElementById('tempimg'); |
40 | obj_img.dynsrc=obj_file.value; |
41 | filesize = obj_img.fileSize; |
42 | }else{ |
43 | alert(tipMsg); |
44 | return; |
45 | } |
46 | if(filesize==-1){ |
47 | alert(tipMsg); |
48 | return; |
49 | }else if(filesize>maxsize){ |
50 | alert(errMsg); |
51 | return; |
52 | }else{ |
53 | alert("文件大小符合要求"); |
54 | return; |
55 | } |
56 | }catch(e){ |
57 | alert(e); |
58 | } |
59 | } |
60 | </ script > |
61 | </ html > |
测试上传的文件大小：
各浏览器中的效果如下：
IE8：
FF(11.0)：
Chrome(19.0.1084.56 m)：
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