How to block special characters in the field

Question

How not to allow the user to enter special characters such as *-/+.,:;[]{}ªº^~?<> in the field of question?

Answer 1

I did it this way, it will allow only letters and numbers:

       document.getElementById("teste").onkeypress = function(e) {
         var chr = String.fromCharCode(e.which);
         if ("1234567890qwertyuioplkjhgfdsazxcvbnmQWERTYUIOPLKJHGFDSAZXCVBNM".indexOf(chr) < 0)
           return false;
       };

<input type="text" name="name" id="teste" />

Answer 2

If you want to do a simple validation only to assist the user in client-side, you can use the pattern.

It is a very easy-to-move HTML5 attribute, here have some examples that solve your problem for example by enabling only letters, letters and numbers, etc.

Example for letters and numbers:

<input type="text" required="required" name="text" pattern="[a-zA-Z0-9]+">

And the best is that it is supported by several browser according to the Can I use.

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Now the validation of the data, I recommend you do on server-side. For example with PHP you can use preg_match:

$pattern = '[a-zA-Z0-9]';
if (preg_match($pattern, $email)){return true;}

You can pass directly:

if (preg_match("/([a-zA-Z0-9])/", $email)){return true;}

This will only accept letter and number characters.

Answer 3

Use Patterns for HTML 5.

Example:

<input type="text" pattern="^[a-zA-Z0-9]+$" />