CODEWITHSUNDEEP
jquery
krish
krish

Reputation: 1117

keypress method for input field validation

I was trying to do simple input field validation to restrict some special characters,I got the following solution for that.
But I am unable to understand that what is happening in this ternary operator
var str = String.fromCharCode(e.charCode ? e.which : e.charCode);
Can anyone explain?please..

$(document).ready(function(){
$('#textarea').keypress(function (e) {
        var regex = new RegExp("^[a-zA-Z0-9 ,.!?]+$");
        var str = String.fromCharCode(e.charCode ? e.which : e.charCode);
        if (regex.test(str)) {
            return true;
        }
        else {
            alert("enter only valid string(123 abc , . ! ?)");
            e.preventDefault();
            return false;
        }
    })
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<label class="col-xs-12">Reason<span class="requiredField">*</span></label> <textarea id="textarea"  rows="2"></textarea>

Upvotes: 1

Views: 937

Answers (2)

Louys Patrice Bessette
Louys Patrice Bessette

Reputation: 33933

A better solution would be to bind this character verification to more events.

  • keypress
  • paste

And for browser compatibility, look for the char code in all possible event attribute.

  • which
  • charCode
  • keyCode

And I added an exception for Enter, as it is a textarea and user may want to change line.

$(document).ready(function(){
  $('#textarea').on("keypress paste",function (e) {
    var regex = new RegExp("^[a-zA-Z0-9 ,.!?]+$");
    var charCode = e.which || e.charCode || e.keyCode;
    
    if(charCode!=13){ // to allow [ENTER]
    
      var str = String.fromCharCode(charCode);
      if (regex.test(str)) {
        return true;
      }
      else {
        alert("enter only valid string(123 abc , . ! ?)");
        e.preventDefault();
        return false;
      }
    }
  })
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<label class="col-xs-12">Reason<span class="requiredField">*</span></label>
<textarea id="textarea"  rows="2"></textarea>

Upvotes: 1

Mayank Pandeyz
Mayank Pandeyz

Reputation: 26258

String.fromCharCode Convert a Unicode number into a character.

var regex = new RegExp("^[a-zA-Z0-9 ,.!?]+$"); Its a regular expression to check if the entered key is from alphabets or numbers or full stop or a comma or a !.

String.fromCharCode(e.charCode ? e.which : e.charCode); this return either the key code of pressed key or the char code.

Ex: var res = String.fromCharCode(65); return A

if (regex.test(str)) { to check whether the key pressed is accepted or not.

Upvotes: 1

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