I'm trying to write a regex for an name field and block all special characters

JS Fiddle: /

However, my code seems to ignore it. Could someone tell what I'm doing wrong?

$('input').on('keypress', function (e) {
var blockSpecialRegex = new RegExp("~`!@#$%^&()_={}\[\]\:;,.\/<>/-+/?");
  var key = String.fromCharCode(!e.charCode ? e.which : e.charCode);
  console.log(key)
  if(blockSpecialRegex.test(key) || $.isNumeric(key)){
    e.preventDefault();
    return false;
  }
  });

I'm trying to write a regex for an name field and block all special characters

JS Fiddle: https://jsfiddle/69mqhzq6/

However, my code seems to ignore it. Could someone tell what I'm doing wrong?

$('input').on('keypress', function (e) {
var blockSpecialRegex = new RegExp("~`!@#$%^&()_={}\[\]\:;,.\/<>/-+/?");
  var key = String.fromCharCode(!e.charCode ? e.which : e.charCode);
  console.log(key)
  if(blockSpecialRegex.test(key) || $.isNumeric(key)){
    e.preventDefault();
    return false;
  }
  });

• javascript
• regex

• 1 Use var blockSpecialRegex = /[~`!@#$%^&()_={}[\]:;,.<>+\/?-]/; – Wiktor Stribiżew Commented Jul 9, 2017 at 19:55
• Thank you, that worked. Any idea why passing it in new RegExp fails? – zer0 Commented Jul 9, 2017 at 19:59
• Yes, you did not define a character class, just enumerated the symbols. – Wiktor Stribiżew Commented Jul 9, 2017 at 20:00
• @ultimatecoder : see my answer why passing it in new RegExp fails. – stomtech Commented Jul 9, 2017 at 20:13

3 Answers 3

You just enumerated the special chars without creating a character class defined with the help of [...].

I suggest using a regex literal with a character class matching any of the symbols defined in it:

var blockSpecialRegex = /[~`!@#$%^&()_={}[\]:;,.<>+\/?-]/;

Note that the - should be at the start/end of the character class to denote a literal - symbol. The ] inside must be escaped, but [ does not have to be escaped. / must be escaped because it is a regex delimiter symbol.

JS code:

$('input').on('keypress', function (e) {
var blockSpecialRegex = /[~`!@#$%^&()_={}[\]:;,.<>+\/?-]/;
  var key = String.fromCharCode(!e.charCode ? e.which : e.charCode);
  console.log(key)
  if(blockSpecialRegex.test(key) || $.isNumeric(key)){
    e.preventDefault();
    return false;
  }
  });

<script src="https://ajax.googleapis./ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<input type="text">

Why not use a regex to allow only alphabets,numbers and spaces(if required) ^[A-Za-z0-9 ]*$

When using the constructor function, the normal string escape rules (preceding special characters with \ when included in a string) are necessary.

So you need to do this:

var blockSpecialRegex = new RegExp("[~`!@#$%^&()_={}\\[\\]\\:;,\\.\\/<>\\\\*\\-+\\?]");

See RegExp - Javascript