js判断上传文件的类型和大小

 1 //检测文件大小和类型

 2 function fileChange(target){

 3 //检测上传文件的类型

 4 if(!(/(?:jpg|gif|png|jpeg)$/i.test(target.value))) {

 5 alert("只允许上传jpg|gif|png|jpeg格式的图片");

 6 if(window.ActiveXObject) {//for IE

 7 target.select();//select the file ,and clear selection

 8 document.selection.clear();

 9 } else if(window.opera) {//for opera

10 target.type="text";target.type="file";

11 } else target.value="";//for FF,Chrome,Safari

12 return;

13 } else {

14 return; //alert("ok");//or you can do nothing here.

15 }

16 

17 //检测上传文件的大小

18 var isIE = /msie/i.test(navigator.userAgent) && !window.opera;

19 var fileSize = 0;

20 if (isIE && !target.files){

21 var filePath = target.value;

22 var fileSystem = new ActiveXObject("Scripting.FileSystemObject");

23 var file = fileSystem.GetFile (filePath);

24 fileSize = file.Size;

25 } else {

26 fileSize = target.files[0].size;

27 }

28 var size = fileSize / 1024;

29 if(size>(500)){

30 alert("文件大小不能超过500KB");

31 if(window.ActiveXObject) {//for IE

32 target.select();//select the file ,and clear selection

33 document.selection.clear();

34 } else if(window.opera) {//for opera

35 target.type="text";target.type="file";

36 } else {

37 target.value="";//for FF,Chrome,Safari

38 }

39 return;

40 }else{

41 return;

42 }

43 }