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how to get file extension using javascript

sandeep thakur
Expand|Select|Wrap|Line Numbers
  1. <html>
  2. <head>
  3. <script type="text/javascript" language="javascript">
  4. function valid(ele)
  5. {
  6.   var file_name= ele.file.value;
  7.  
  8.  
  9.   var file_array = file_name.split(".");
  10.  
  11.   var file_array1 = file_array[1].toLowerCase();   
  12.  
  13.  
  14.   if (file_array1 == 'gif' || file_array1 == 'jpg' || file_array1 == 'jpeg',file_array1=='gif')
  15.   {
  16.     return true;  
  17.   }
  18.   else {
  19.  
  20.        alert("Please Upload Valid Image File");
  21.        ele.file.focus();
  22.        return false;
  23.   }      
  24.  
  25. }
  26. </script>
  27.  
  28. </head>
  29. <body>
  30.  
  31. <form name="form1" action="upload_file.php" method="post" enctype="multipart/form-data" onsubmit="return valid(this);">
  32. <label for="file">Filename:</label>
  33. <input type="file" name="file" id="file" /> 
  34. <br />
  35. <input type="submit" name="submit" value="Submit" />
  36. </form>
  37.  
  38. </body>
  39. </html>
Dec 11 '10 #1
1 9045
gits
5,390 Expert Mod 4TB
line 14 is quite weird ... the following part:
Expand|Select|Wrap|Line Numbers
  1. file_array1 == 'jpeg',file_array1=='gif'
will avoid to match 'jpeg' since the first 2 conditions are false and the comma-operator will force the execution of the 'gif' check again at last and so 'jpeg' will never match. just drop everything after the comma.

it could be simply improved to add more filetypes when using a filetype-map like:
Expand|Select|Wrap|Line Numbers
  1. var ft = { 'gif': 1, 'jpg': 1, 'png': 1 };
  2.  
  3. // now use a simple existence-check like:
  4. if (splittedFileType in ft) {
  5.     // valid
  6. } else {
  7.     // invalid
  8. }
  9.  
Dec 12 '10 #2

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