[javascript] RegEx for Javascript to allow only alphanumeric

Jquery to accept only NUMBERS, ALPHABETS and SPECIAL CHARECTERS

_x000D_
_x000D_
<html>_x000D_
<head>_x000D_
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>_x000D_
</head>_x000D_
_x000D_
<body>_x000D_
Enter Only Numbers: _x000D_
<input type="text" id="onlynumbers">_x000D_
<br><br>_x000D_
Enter Only Alphabets: _x000D_
<input type="text" id="onlyalpha">_x000D_
<br><br>_x000D_
Enter other than Alphabets and numbers like special characters: _x000D_
<input type="text" id="speclchar">_x000D_
_x000D_
<script>_x000D_
    $('#onlynumbers').keypress(function(e) {_x000D_
      var letters=/^[0-9]/g; //g means global_x000D_
      if(!(e.key).match(letters)) e.preventDefault();_x000D_
 });_x000D_
    _x000D_
    $('#onlyalpha').keypress(function(e) {_x000D_
      var letters=/^[a-z]/gi; //i means ignorecase_x000D_
      if(!(e.key).match(letters)) e.preventDefault();_x000D_
 });_x000D_
    _x000D_
    $('#speclchar').keypress(function(e) {_x000D_
      var letters=/^[0-9a-z]/gi; _x000D_
      if((e.key).match(letters)) e.preventDefault();_x000D_
 });_x000D_
    </script>_x000D_
</body>_x000D_
</html>
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**JQUERY to accept only NUMBERS , ALPHABETS and SPECIAL CHARACTERS **


<!DOCTYPE html>
    $('#onlynumbers').keypress(function(e) {
      var letters=/^[0-9]/g; //g means global
      if(!(e.key).match(letters)) e.preventDefault();
    });

    $('#onlyalpha').keypress(function(e) {
      var letters=/^[a-z]/gi; //i means ignorecase
      if(!(e.key).match(letters)) e.preventDefault();
    });

    $('#speclchar').keypress(function(e) {
      var letters=/^[0-9a-z]/gi; 
      if((e.key).match(letters)) e.preventDefault();
    });
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"> 

Enter Only Numbers:

Enter Only Alphabets:

Enter other than Alphabets and numbers like special characters:

</body>
</html>