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How can I create a regex for folder names in javascript?

I want to check the folder name, it should not start with a number or any special character, I'm not sure what special characters are allowed inside folder names, kindly help.

here is my function

function validateFileName() { 
    var re = /[^a-zA-Z0-9\-]/;

      if(!re.test($('#new_folder_name').value)) {
          alert("Error: Input contains invalid characters!");
          $('#new_folder_name').focus();
          return false;
        }

        // validation was successful
        return true;
      }
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3 answers


Just check that the folder name starts with a letter and does not start with . (Dot)

var re = /^[a-zA-Z].*/;
re.test(folder_name);


This will return true only if the folder name starts with a letter.

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There is a function in C # that returns a list of invalid path characters . In addition, Naming Files, Paths, and Namespaces contains a list of reserved characters that cannot be used in both folder names and files. Here is a regular expression that covers all of these restrictions:

var RealInvalidPathChars = /[<>:"\/\\|?*\x00-\x1F]/;

You can check for any of the characters inside the string and that will be the wrong way.

In addition, there is a list of reserved words that cannot be used as folder names, and we can also use them in a regular expression:

/^(?:aux|con|clock\$|nul|prn|com[1-9]|lpt[1-9])$/i


If this regular check returns true, the path is invalid.

Here's a snippet that brings it all together:

$( "#new_folder_name" ).submit(function( event ) {
    var rx = /[<>:"\/\\|?*\x00-\x1F]|^(?:aux|con|clock\$|nul|prn|com[1-9]|lpt[1-9])$/i;
    if(rx.test($( "input:first" ).val())) {
      alert("Error: Input contains invalid characters!");
   }
});
      

        
        
        
      

    
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form id="new_folder_name">
  <input type="text" value="<INVALID>">
  <input type="submit" value="Go">
</form>
Run codeHide result


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According to File Naming, Path and Namespace on MSDN

The following special characters are retained:

< (less than)
> (greater than)
: (colon)
" (double quote)
/ (forward slash)
\ (backslash)
| (vertical bar or pipe)
? (question mark)
* (asterisk)

And the following keywords are also reserved

CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9, LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, and LPT9.

Which are insensitive to the case.

So, given these facts, a possible regex could be:

[^<>:"/\|?*(?:aux|con|nul|prn|com[1-9]|lpt[1-9])]

So your converted function will be

function validateFileName() { 
    var re = /[^<>:"/\|?*(?:aux|con|nul|prn|com[1-9]|lpt[1-9])]/;

      if(!re.test($('#new_folder_name').value)) {
          alert("Error: Input contains invalid characters!");
          $('#new_folder_name').focus();
          return false;
        }

        // validation was successful
        return true;
      }
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